| /* |
| * Copyright (c) 2013, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.lang; |
| |
| import java.io.InputStream; |
| import java.io.IOException; |
| import java.io.UncheckedIOException; |
| import java.io.File; |
| import java.lang.reflect.Constructor; |
| import java.net.URL; |
| import java.security.AccessController; |
| import java.security.AccessControlContext; |
| import java.security.CodeSource; |
| import java.security.PrivilegedAction; |
| import java.security.ProtectionDomain; |
| import java.security.cert.Certificate; |
| import java.util.Collections; |
| import java.util.Enumeration; |
| import java.util.HashMap; |
| import java.util.Hashtable; |
| import java.util.Map; |
| import java.util.NoSuchElementException; |
| import java.util.Objects; |
| import java.util.Set; |
| import java.util.Spliterator; |
| import java.util.Spliterators; |
| import java.util.Stack; |
| import java.util.Vector; |
| import java.util.WeakHashMap; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.function.Supplier; |
| import java.util.stream.Stream; |
| import java.util.stream.StreamSupport; |
| |
| import jdk.internal.perf.PerfCounter; |
| import jdk.internal.loader.BootLoader; |
| import jdk.internal.loader.ClassLoaders; |
| import jdk.internal.misc.SharedSecrets; |
| import jdk.internal.misc.Unsafe; |
| import jdk.internal.misc.VM; |
| import jdk.internal.reflect.CallerSensitive; |
| import jdk.internal.reflect.Reflection; |
| import sun.reflect.misc.ReflectUtil; |
| import sun.security.util.SecurityConstants; |
| |
| /** |
| * A class loader is an object that is responsible for loading classes. The |
| * class {@code ClassLoader} is an abstract class. Given the <a |
| * href="#name">binary name</a> of a class, a class loader should attempt to |
| * locate or generate data that constitutes a definition for the class. A |
| * typical strategy is to transform the name into a file name and then read a |
| * "class file" of that name from a file system. |
| * |
| * <p> Every {@link java.lang.Class Class} object contains a {@link |
| * Class#getClassLoader() reference} to the {@code ClassLoader} that defined |
| * it. |
| * |
| * <p> {@code Class} objects for array classes are not created by class |
| * loaders, but are created automatically as required by the Java runtime. |
| * The class loader for an array class, as returned by {@link |
| * Class#getClassLoader()} is the same as the class loader for its element |
| * type; if the element type is a primitive type, then the array class has no |
| * class loader. |
| * |
| * <p> Applications implement subclasses of {@code ClassLoader} in order to |
| * extend the manner in which the Java virtual machine dynamically loads |
| * classes. |
| * |
| * <p> Class loaders may typically be used by security managers to indicate |
| * security domains. |
| * |
| * <p> In addition to loading classes, a class loader is also responsible for |
| * locating resources. A resource is some data (a "{@code .class}" file, |
| * configuration data, or an image for example) that is identified with an |
| * abstract '/'-separated path name. Resources are typically packaged with an |
| * application or library so that they can be located by code in the |
| * application or library. In some cases, the resources are included so that |
| * they can be located by other libraries. |
| * |
| * <p> The {@code ClassLoader} class uses a delegation model to search for |
| * classes and resources. Each instance of {@code ClassLoader} has an |
| * associated parent class loader. When requested to find a class or |
| * resource, a {@code ClassLoader} instance will usually delegate the search |
| * for the class or resource to its parent class loader before attempting to |
| * find the class or resource itself. |
| * |
| * <p> Class loaders that support concurrent loading of classes are known as |
| * <em>{@linkplain #isRegisteredAsParallelCapable() parallel capable}</em> class |
| * loaders and are required to register themselves at their class initialization |
| * time by invoking the {@link |
| * #registerAsParallelCapable ClassLoader.registerAsParallelCapable} |
| * method. Note that the {@code ClassLoader} class is registered as parallel |
| * capable by default. However, its subclasses still need to register themselves |
| * if they are parallel capable. |
| * In environments in which the delegation model is not strictly |
| * hierarchical, class loaders need to be parallel capable, otherwise class |
| * loading can lead to deadlocks because the loader lock is held for the |
| * duration of the class loading process (see {@link #loadClass |
| * loadClass} methods). |
| * |
| * <h3> <a id="builtinLoaders">Run-time Built-in Class Loaders</a></h3> |
| * |
| * The Java run-time has the following built-in class loaders: |
| * |
| * <ul> |
| * <li><p>Bootstrap class loader. |
| * It is the virtual machine's built-in class loader, typically represented |
| * as {@code null}, and does not have a parent.</li> |
| * <li><p>{@linkplain #getPlatformClassLoader() Platform class loader}. |
| * All <em>platform classes</em> are visible to the platform class loader |
| * that can be used as the parent of a {@code ClassLoader} instance. |
| * Platform classes include Java SE platform APIs, their implementation |
| * classes and JDK-specific run-time classes that are defined by the |
| * platform class loader or its ancestors. |
| * <p> To allow for upgrading/overriding of modules defined to the platform |
| * class loader, and where upgraded modules read modules defined to class |
| * loaders other than the platform class loader and its ancestors, then |
| * the platform class loader may have to delegate to other class loaders, |
| * the application class loader for example. |
| * In other words, classes in named modules defined to class loaders |
| * other than the platform class loader and its ancestors may be visible |
| * to the platform class loader. </li> |
| * <li><p>{@linkplain #getSystemClassLoader() System class loader}. |
| * It is also known as <em>application class loader</em> and is distinct |
| * from the platform class loader. |
| * The system class loader is typically used to define classes on the |
| * application class path, module path, and JDK-specific tools. |
| * The platform class loader is a parent or an ancestor of the system class |
| * loader that all platform classes are visible to it.</li> |
| * </ul> |
| * |
| * <p> Normally, the Java virtual machine loads classes from the local file |
| * system in a platform-dependent manner. |
| * However, some classes may not originate from a file; they may originate |
| * from other sources, such as the network, or they could be constructed by an |
| * application. The method {@link #defineClass(String, byte[], int, int) |
| * defineClass} converts an array of bytes into an instance of class |
| * {@code Class}. Instances of this newly defined class can be created using |
| * {@link Class#newInstance Class.newInstance}. |
| * |
| * <p> The methods and constructors of objects created by a class loader may |
| * reference other classes. To determine the class(es) referred to, the Java |
| * virtual machine invokes the {@link #loadClass loadClass} method of |
| * the class loader that originally created the class. |
| * |
| * <p> For example, an application could create a network class loader to |
| * download class files from a server. Sample code might look like: |
| * |
| * <blockquote><pre> |
| * ClassLoader loader = new NetworkClassLoader(host, port); |
| * Object main = loader.loadClass("Main", true).newInstance(); |
| * . . . |
| * </pre></blockquote> |
| * |
| * <p> The network class loader subclass must define the methods {@link |
| * #findClass findClass} and {@code loadClassData} to load a class |
| * from the network. Once it has downloaded the bytes that make up the class, |
| * it should use the method {@link #defineClass defineClass} to |
| * create a class instance. A sample implementation is: |
| * |
| * <blockquote><pre> |
| * class NetworkClassLoader extends ClassLoader { |
| * String host; |
| * int port; |
| * |
| * public Class findClass(String name) { |
| * byte[] b = loadClassData(name); |
| * return defineClass(name, b, 0, b.length); |
| * } |
| * |
| * private byte[] loadClassData(String name) { |
| * // load the class data from the connection |
| * . . . |
| * } |
| * } |
| * </pre></blockquote> |
| * |
| * <h3> <a id="name">Binary names</a> </h3> |
| * |
| * <p> Any class name provided as a {@code String} parameter to methods in |
| * {@code ClassLoader} must be a binary name as defined by |
| * <cite>The Java™ Language Specification</cite>. |
| * |
| * <p> Examples of valid class names include: |
| * <blockquote><pre> |
| * "java.lang.String" |
| * "javax.swing.JSpinner$DefaultEditor" |
| * "java.security.KeyStore$Builder$FileBuilder$1" |
| * "java.net.URLClassLoader$3$1" |
| * </pre></blockquote> |
| * |
| * <p> Any package name provided as a {@code String} parameter to methods in |
| * {@code ClassLoader} must be either the empty string (denoting an unnamed package) |
| * or a fully qualified name as defined by |
| * <cite>The Java™ Language Specification</cite>. |
| * |
| * @jls 6.7 Fully Qualified Names |
| * @jls 13.1 The Form of a Binary |
| * @see #resolveClass(Class) |
| * @since 1.0 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public abstract class ClassLoader { |
| |
| private static native void registerNatives(); |
| static { |
| registerNatives(); |
| } |
| |
| // The parent class loader for delegation |
| // Note: VM hardcoded the offset of this field, thus all new fields |
| // must be added *after* it. |
| private final ClassLoader parent; |
| |
| // class loader name |
| private final String name; |
| |
| // the unnamed module for this ClassLoader |
| private final Module unnamedModule; |
| |
| /** |
| * Encapsulates the set of parallel capable loader types. |
| */ |
| private static class ParallelLoaders { |
| private ParallelLoaders() {} |
| |
| // the set of parallel capable loader types |
| private static final Set<Class<? extends ClassLoader>> loaderTypes = |
| Collections.newSetFromMap(new WeakHashMap<>()); |
| static { |
| synchronized (loaderTypes) { loaderTypes.add(ClassLoader.class); } |
| } |
| |
| /** |
| * Registers the given class loader type as parallel capable. |
| * Returns {@code true} is successfully registered; {@code false} if |
| * loader's super class is not registered. |
| */ |
| static boolean register(Class<? extends ClassLoader> c) { |
| synchronized (loaderTypes) { |
| if (loaderTypes.contains(c.getSuperclass())) { |
| // register the class loader as parallel capable |
| // if and only if all of its super classes are. |
| // Note: given current classloading sequence, if |
| // the immediate super class is parallel capable, |
| // all the super classes higher up must be too. |
| loaderTypes.add(c); |
| return true; |
| } else { |
| return false; |
| } |
| } |
| } |
| |
| /** |
| * Returns {@code true} if the given class loader type is |
| * registered as parallel capable. |
| */ |
| static boolean isRegistered(Class<? extends ClassLoader> c) { |
| synchronized (loaderTypes) { |
| return loaderTypes.contains(c); |
| } |
| } |
| } |
| |
| // Maps class name to the corresponding lock object when the current |
| // class loader is parallel capable. |
| // Note: VM also uses this field to decide if the current class loader |
| // is parallel capable and the appropriate lock object for class loading. |
| private final ConcurrentHashMap<String, Object> parallelLockMap; |
| |
| // Maps packages to certs |
| private final Map <String, Certificate[]> package2certs; |
| |
| // Shared among all packages with unsigned classes |
| private static final Certificate[] nocerts = new Certificate[0]; |
| |
| // The classes loaded by this class loader. The only purpose of this table |
| // is to keep the classes from being GC'ed until the loader is GC'ed. |
| private final Vector<Class<?>> classes = new Vector<>(); |
| |
| // The "default" domain. Set as the default ProtectionDomain on newly |
| // created classes. |
| private final ProtectionDomain defaultDomain = |
| new ProtectionDomain(new CodeSource(null, (Certificate[]) null), |
| null, this, null); |
| |
| // Invoked by the VM to record every loaded class with this loader. |
| void addClass(Class<?> c) { |
| classes.addElement(c); |
| } |
| |
| // The packages defined in this class loader. Each package name is |
| // mapped to its corresponding NamedPackage object. |
| // |
| // The value is a Package object if ClassLoader::definePackage, |
| // Class::getPackage, ClassLoader::getDefinePackage(s) or |
| // Package::getPackage(s) method is called to define it. |
| // Otherwise, the value is a NamedPackage object. |
| private final ConcurrentHashMap<String, NamedPackage> packages |
| = new ConcurrentHashMap<>(); |
| |
| /* |
| * Returns a named package for the given module. |
| */ |
| private NamedPackage getNamedPackage(String pn, Module m) { |
| NamedPackage p = packages.get(pn); |
| if (p == null) { |
| p = new NamedPackage(pn, m); |
| |
| NamedPackage value = packages.putIfAbsent(pn, p); |
| if (value != null) { |
| // Package object already be defined for the named package |
| p = value; |
| // if definePackage is called by this class loader to define |
| // a package in a named module, this will return Package |
| // object of the same name. Package object may contain |
| // unexpected information but it does not impact the runtime. |
| // this assertion may be helpful for troubleshooting |
| assert value.module() == m; |
| } |
| } |
| return p; |
| } |
| |
| private static Void checkCreateClassLoader() { |
| return checkCreateClassLoader(null); |
| } |
| |
| private static Void checkCreateClassLoader(String name) { |
| if (name != null && name.isEmpty()) { |
| throw new IllegalArgumentException("name must be non-empty or null"); |
| } |
| |
| SecurityManager security = System.getSecurityManager(); |
| if (security != null) { |
| security.checkCreateClassLoader(); |
| } |
| return null; |
| } |
| |
| private ClassLoader(Void unused, String name, ClassLoader parent) { |
| this.name = name; |
| this.parent = parent; |
| this.unnamedModule = new Module(this); |
| if (ParallelLoaders.isRegistered(this.getClass())) { |
| parallelLockMap = new ConcurrentHashMap<>(); |
| package2certs = new ConcurrentHashMap<>(); |
| assertionLock = new Object(); |
| } else { |
| // no finer-grained lock; lock on the classloader instance |
| parallelLockMap = null; |
| package2certs = new Hashtable<>(); |
| assertionLock = this; |
| } |
| } |
| |
| /** |
| * Creates a new class loader of the specified name and using the |
| * specified parent class loader for delegation. |
| * |
| * @apiNote If the parent is specified as {@code null} (for the |
| * bootstrap class loader) then there is no guarantee that all platform |
| * classes are visible. |
| * |
| * @param name class loader name; or {@code null} if not named |
| * @param parent the parent class loader |
| * |
| * @throws IllegalArgumentException if the given name is empty. |
| * |
| * @throws SecurityException |
| * If a security manager exists and its |
| * {@link SecurityManager#checkCreateClassLoader()} |
| * method doesn't allow creation of a new class loader. |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| protected ClassLoader(String name, ClassLoader parent) { |
| this(checkCreateClassLoader(name), name, parent); |
| } |
| |
| /** |
| * Creates a new class loader using the specified parent class loader for |
| * delegation. |
| * |
| * <p> If there is a security manager, its {@link |
| * SecurityManager#checkCreateClassLoader() checkCreateClassLoader} method |
| * is invoked. This may result in a security exception. </p> |
| * |
| * @apiNote If the parent is specified as {@code null} (for the |
| * bootstrap class loader) then there is no guarantee that all platform |
| * classes are visible. |
| * |
| * @param parent |
| * The parent class loader |
| * |
| * @throws SecurityException |
| * If a security manager exists and its |
| * {@code checkCreateClassLoader} method doesn't allow creation |
| * of a new class loader. |
| * |
| * @since 1.2 |
| */ |
| protected ClassLoader(ClassLoader parent) { |
| this(checkCreateClassLoader(), null, parent); |
| } |
| |
| /** |
| * Creates a new class loader using the {@code ClassLoader} returned by |
| * the method {@link #getSystemClassLoader() |
| * getSystemClassLoader()} as the parent class loader. |
| * |
| * <p> If there is a security manager, its {@link |
| * SecurityManager#checkCreateClassLoader() |
| * checkCreateClassLoader} method is invoked. This may result in |
| * a security exception. </p> |
| * |
| * @throws SecurityException |
| * If a security manager exists and its |
| * {@code checkCreateClassLoader} method doesn't allow creation |
| * of a new class loader. |
| */ |
| protected ClassLoader() { |
| this(checkCreateClassLoader(), null, getSystemClassLoader()); |
| } |
| |
| /** |
| * Returns the name of this class loader or {@code null} if |
| * this class loader is not named. |
| * |
| * @apiNote This method is non-final for compatibility. If this |
| * method is overridden, this method must return the same name |
| * as specified when this class loader was instantiated. |
| * |
| * @return name of this class loader; or {@code null} if |
| * this class loader is not named. |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| public String getName() { |
| return name; |
| } |
| |
| // package-private used by StackTraceElement to avoid |
| // calling the overrideable getName method |
| final String name() { |
| return name; |
| } |
| |
| // -- Class -- |
| |
| /** |
| * Loads the class with the specified <a href="#name">binary name</a>. |
| * This method searches for classes in the same manner as the {@link |
| * #loadClass(String, boolean)} method. It is invoked by the Java virtual |
| * machine to resolve class references. Invoking this method is equivalent |
| * to invoking {@link #loadClass(String, boolean) loadClass(name, |
| * false)}. |
| * |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The resulting {@code Class} object |
| * |
| * @throws ClassNotFoundException |
| * If the class was not found |
| */ |
| public Class<?> loadClass(String name) throws ClassNotFoundException { |
| return loadClass(name, false); |
| } |
| |
| /** |
| * Loads the class with the specified <a href="#name">binary name</a>. The |
| * default implementation of this method searches for classes in the |
| * following order: |
| * |
| * <ol> |
| * |
| * <li><p> Invoke {@link #findLoadedClass(String)} to check if the class |
| * has already been loaded. </p></li> |
| * |
| * <li><p> Invoke the {@link #loadClass(String) loadClass} method |
| * on the parent class loader. If the parent is {@code null} the class |
| * loader built into the virtual machine is used, instead. </p></li> |
| * |
| * <li><p> Invoke the {@link #findClass(String)} method to find the |
| * class. </p></li> |
| * |
| * </ol> |
| * |
| * <p> If the class was found using the above steps, and the |
| * {@code resolve} flag is true, this method will then invoke the {@link |
| * #resolveClass(Class)} method on the resulting {@code Class} object. |
| * |
| * <p> Subclasses of {@code ClassLoader} are encouraged to override {@link |
| * #findClass(String)}, rather than this method. </p> |
| * |
| * <p> Unless overridden, this method synchronizes on the result of |
| * {@link #getClassLoadingLock getClassLoadingLock} method |
| * during the entire class loading process. |
| * |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @param resolve |
| * If {@code true} then resolve the class |
| * |
| * @return The resulting {@code Class} object |
| * |
| * @throws ClassNotFoundException |
| * If the class could not be found |
| */ |
| protected Class<?> loadClass(String name, boolean resolve) |
| throws ClassNotFoundException |
| { |
| synchronized (getClassLoadingLock(name)) { |
| // First, check if the class has already been loaded |
| Class<?> c = findLoadedClass(name); |
| if (c == null) { |
| long t0 = System.nanoTime(); |
| try { |
| if (parent != null) { |
| c = parent.loadClass(name, false); |
| } else { |
| c = findBootstrapClassOrNull(name); |
| } |
| } catch (ClassNotFoundException e) { |
| // ClassNotFoundException thrown if class not found |
| // from the non-null parent class loader |
| } |
| |
| if (c == null) { |
| // If still not found, then invoke findClass in order |
| // to find the class. |
| long t1 = System.nanoTime(); |
| c = findClass(name); |
| |
| // this is the defining class loader; record the stats |
| PerfCounter.getParentDelegationTime().addTime(t1 - t0); |
| PerfCounter.getFindClassTime().addElapsedTimeFrom(t1); |
| PerfCounter.getFindClasses().increment(); |
| } |
| } |
| if (resolve) { |
| resolveClass(c); |
| } |
| return c; |
| } |
| } |
| |
| /** |
| * Loads the class with the specified <a href="#name">binary name</a> |
| * in a module defined to this class loader. This method returns {@code null} |
| * if the class could not be found. |
| * |
| * @apiNote This method does not delegate to the parent class loader. |
| * |
| * @implSpec The default implementation of this method searches for classes |
| * in the following order: |
| * |
| * <ol> |
| * <li>Invoke {@link #findLoadedClass(String)} to check if the class |
| * has already been loaded.</li> |
| * <li>Invoke the {@link #findClass(String, String)} method to find the |
| * class in the given module.</li> |
| * </ol> |
| * |
| * @param module |
| * The module |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The resulting {@code Class} object in a module defined by |
| * this class loader, or {@code null} if the class could not be found. |
| */ |
| final Class<?> loadClass(Module module, String name) { |
| synchronized (getClassLoadingLock(name)) { |
| // First, check if the class has already been loaded |
| Class<?> c = findLoadedClass(name); |
| if (c == null) { |
| c = findClass(module.getName(), name); |
| } |
| if (c != null && c.getModule() == module) { |
| return c; |
| } else { |
| return null; |
| } |
| } |
| } |
| |
| /** |
| * Returns the lock object for class loading operations. |
| * For backward compatibility, the default implementation of this method |
| * behaves as follows. If this ClassLoader object is registered as |
| * parallel capable, the method returns a dedicated object associated |
| * with the specified class name. Otherwise, the method returns this |
| * ClassLoader object. |
| * |
| * @param className |
| * The name of the to-be-loaded class |
| * |
| * @return the lock for class loading operations |
| * |
| * @throws NullPointerException |
| * If registered as parallel capable and {@code className} is null |
| * |
| * @see #loadClass(String, boolean) |
| * |
| * @since 1.7 |
| */ |
| protected Object getClassLoadingLock(String className) { |
| Object lock = this; |
| if (parallelLockMap != null) { |
| Object newLock = new Object(); |
| lock = parallelLockMap.putIfAbsent(className, newLock); |
| if (lock == null) { |
| lock = newLock; |
| } |
| } |
| return lock; |
| } |
| |
| // This method is invoked by the virtual machine to load a class. |
| private Class<?> loadClassInternal(String name) |
| throws ClassNotFoundException |
| { |
| // For backward compatibility, explicitly lock on 'this' when |
| // the current class loader is not parallel capable. |
| if (parallelLockMap == null) { |
| synchronized (this) { |
| return loadClass(name); |
| } |
| } else { |
| return loadClass(name); |
| } |
| } |
| |
| // Invoked by the VM after loading class with this loader. |
| private void checkPackageAccess(Class<?> cls, ProtectionDomain pd) { |
| final SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| if (ReflectUtil.isNonPublicProxyClass(cls)) { |
| for (Class<?> intf: cls.getInterfaces()) { |
| checkPackageAccess(intf, pd); |
| } |
| return; |
| } |
| |
| final String name = cls.getName(); |
| final int i = name.lastIndexOf('.'); |
| if (i != -1) { |
| AccessController.doPrivileged(new PrivilegedAction<>() { |
| public Void run() { |
| sm.checkPackageAccess(name.substring(0, i)); |
| return null; |
| } |
| }, new AccessControlContext(new ProtectionDomain[] {pd})); |
| } |
| } |
| } |
| |
| /** |
| * Finds the class with the specified <a href="#name">binary name</a>. |
| * This method should be overridden by class loader implementations that |
| * follow the delegation model for loading classes, and will be invoked by |
| * the {@link #loadClass loadClass} method after checking the |
| * parent class loader for the requested class. |
| * |
| * @implSpec The default implementation throws {@code ClassNotFoundException}. |
| * |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The resulting {@code Class} object |
| * |
| * @throws ClassNotFoundException |
| * If the class could not be found |
| * |
| * @since 1.2 |
| */ |
| protected Class<?> findClass(String name) throws ClassNotFoundException { |
| throw new ClassNotFoundException(name); |
| } |
| |
| /** |
| * Finds the class with the given <a href="#name">binary name</a> |
| * in a module defined to this class loader. |
| * Class loader implementations that support the loading from modules |
| * should override this method. |
| * |
| * @apiNote This method returns {@code null} rather than throwing |
| * {@code ClassNotFoundException} if the class could not be found. |
| * |
| * @implSpec The default implementation attempts to find the class by |
| * invoking {@link #findClass(String)} when the {@code moduleName} is |
| * {@code null}. It otherwise returns {@code null}. |
| * |
| * @param moduleName |
| * The module name; or {@code null} to find the class in the |
| * {@linkplain #getUnnamedModule() unnamed module} for this |
| * class loader |
| |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The resulting {@code Class} object, or {@code null} |
| * if the class could not be found. |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| protected Class<?> findClass(String moduleName, String name) { |
| if (moduleName == null) { |
| try { |
| return findClass(name); |
| } catch (ClassNotFoundException ignore) { } |
| } |
| return null; |
| } |
| |
| |
| /** |
| * Converts an array of bytes into an instance of class {@code Class}. |
| * Before the {@code Class} can be used it must be resolved. This method |
| * is deprecated in favor of the version that takes a <a |
| * href="#name">binary name</a> as its first argument, and is more secure. |
| * |
| * @param b |
| * The bytes that make up the class data. The bytes in positions |
| * {@code off} through {@code off+len-1} should have the format |
| * of a valid class file as defined by |
| * <cite>The Java™ Virtual Machine Specification</cite>. |
| * |
| * @param off |
| * The start offset in {@code b} of the class data |
| * |
| * @param len |
| * The length of the class data |
| * |
| * @return The {@code Class} object that was created from the specified |
| * class data |
| * |
| * @throws ClassFormatError |
| * If the data did not contain a valid class |
| * |
| * @throws IndexOutOfBoundsException |
| * If either {@code off} or {@code len} is negative, or if |
| * {@code off+len} is greater than {@code b.length}. |
| * |
| * @throws SecurityException |
| * If an attempt is made to add this class to a package that |
| * contains classes that were signed by a different set of |
| * certificates than this class, or if an attempt is made |
| * to define a class in a package with a fully-qualified name |
| * that starts with "{@code java.}". |
| * |
| * @see #loadClass(String, boolean) |
| * @see #resolveClass(Class) |
| * |
| * @deprecated Replaced by {@link #defineClass(String, byte[], int, int) |
| * defineClass(String, byte[], int, int)} |
| */ |
| @Deprecated(since="1.1") |
| protected final Class<?> defineClass(byte[] b, int off, int len) |
| throws ClassFormatError |
| { |
| return defineClass(null, b, off, len, null); |
| } |
| |
| /** |
| * Converts an array of bytes into an instance of class {@code Class}. |
| * Before the {@code Class} can be used it must be resolved. |
| * |
| * <p> This method assigns a default {@link java.security.ProtectionDomain |
| * ProtectionDomain} to the newly defined class. The |
| * {@code ProtectionDomain} is effectively granted the same set of |
| * permissions returned when {@link |
| * java.security.Policy#getPermissions(java.security.CodeSource) |
| * Policy.getPolicy().getPermissions(new CodeSource(null, null))} |
| * is invoked. The default protection domain is created on the first invocation |
| * of {@link #defineClass(String, byte[], int, int) defineClass}, |
| * and re-used on subsequent invocations. |
| * |
| * <p> To assign a specific {@code ProtectionDomain} to the class, use |
| * the {@link #defineClass(String, byte[], int, int, |
| * java.security.ProtectionDomain) defineClass} method that takes a |
| * {@code ProtectionDomain} as one of its arguments. </p> |
| * |
| * <p> |
| * This method defines a package in this class loader corresponding to the |
| * package of the {@code Class} (if such a package has not already been defined |
| * in this class loader). The name of the defined package is derived from |
| * the <a href="#name">binary name</a> of the class specified by |
| * the byte array {@code b}. |
| * Other properties of the defined package are as specified by {@link Package}. |
| * |
| * @param name |
| * The expected <a href="#name">binary name</a> of the class, or |
| * {@code null} if not known |
| * |
| * @param b |
| * The bytes that make up the class data. The bytes in positions |
| * {@code off} through {@code off+len-1} should have the format |
| * of a valid class file as defined by |
| * <cite>The Java™ Virtual Machine Specification</cite>. |
| * |
| * @param off |
| * The start offset in {@code b} of the class data |
| * |
| * @param len |
| * The length of the class data |
| * |
| * @return The {@code Class} object that was created from the specified |
| * class data. |
| * |
| * @throws ClassFormatError |
| * If the data did not contain a valid class |
| * |
| * @throws IndexOutOfBoundsException |
| * If either {@code off} or {@code len} is negative, or if |
| * {@code off+len} is greater than {@code b.length}. |
| * |
| * @throws SecurityException |
| * If an attempt is made to add this class to a package that |
| * contains classes that were signed by a different set of |
| * certificates than this class (which is unsigned), or if |
| * {@code name} begins with "{@code java.}". |
| * |
| * @see #loadClass(String, boolean) |
| * @see #resolveClass(Class) |
| * @see java.security.CodeSource |
| * @see java.security.SecureClassLoader |
| * |
| * @since 1.1 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected final Class<?> defineClass(String name, byte[] b, int off, int len) |
| throws ClassFormatError |
| { |
| return defineClass(name, b, off, len, null); |
| } |
| |
| /* Determine protection domain, and check that: |
| - not define java.* class, |
| - signer of this class matches signers for the rest of the classes in |
| package. |
| */ |
| private ProtectionDomain preDefineClass(String name, |
| ProtectionDomain pd) |
| { |
| if (!checkName(name)) |
| throw new NoClassDefFoundError("IllegalName: " + name); |
| |
| // Note: Checking logic in java.lang.invoke.MemberName.checkForTypeAlias |
| // relies on the fact that spoofing is impossible if a class has a name |
| // of the form "java.*" |
| if ((name != null) && name.startsWith("java.") |
| && this != getBuiltinPlatformClassLoader()) { |
| throw new SecurityException |
| ("Prohibited package name: " + |
| name.substring(0, name.lastIndexOf('.'))); |
| } |
| if (pd == null) { |
| pd = defaultDomain; |
| } |
| |
| if (name != null) { |
| checkCerts(name, pd.getCodeSource()); |
| } |
| |
| return pd; |
| } |
| |
| private String defineClassSourceLocation(ProtectionDomain pd) { |
| CodeSource cs = pd.getCodeSource(); |
| String source = null; |
| if (cs != null && cs.getLocation() != null) { |
| source = cs.getLocation().toString(); |
| } |
| return source; |
| } |
| |
| private void postDefineClass(Class<?> c, ProtectionDomain pd) { |
| // define a named package, if not present |
| getNamedPackage(c.getPackageName(), c.getModule()); |
| |
| if (pd.getCodeSource() != null) { |
| Certificate certs[] = pd.getCodeSource().getCertificates(); |
| if (certs != null) |
| setSigners(c, certs); |
| } |
| } |
| |
| /** |
| * Converts an array of bytes into an instance of class {@code Class}, |
| * with a given {@code ProtectionDomain}. |
| * |
| * <p> If the given {@code ProtectionDomain} is {@code null}, |
| * then a default protection domain will be assigned to the class as specified |
| * in the documentation for {@link #defineClass(String, byte[], int, int)}. |
| * Before the class can be used it must be resolved. |
| * |
| * <p> The first class defined in a package determines the exact set of |
| * certificates that all subsequent classes defined in that package must |
| * contain. The set of certificates for a class is obtained from the |
| * {@link java.security.CodeSource CodeSource} within the |
| * {@code ProtectionDomain} of the class. Any classes added to that |
| * package must contain the same set of certificates or a |
| * {@code SecurityException} will be thrown. Note that if |
| * {@code name} is {@code null}, this check is not performed. |
| * You should always pass in the <a href="#name">binary name</a> of the |
| * class you are defining as well as the bytes. This ensures that the |
| * class you are defining is indeed the class you think it is. |
| * |
| * <p> If the specified {@code name} begins with "{@code java.}", it can |
| * only be defined by the {@linkplain #getPlatformClassLoader() |
| * platform class loader} or its ancestors; otherwise {@code SecurityException} |
| * will be thrown. If {@code name} is not {@code null}, it must be equal to |
| * the <a href="#name">binary name</a> of the class |
| * specified by the byte array {@code b}, otherwise a {@link |
| * NoClassDefFoundError NoClassDefFoundError} will be thrown. |
| * |
| * <p> This method defines a package in this class loader corresponding to the |
| * package of the {@code Class} (if such a package has not already been defined |
| * in this class loader). The name of the defined package is derived from |
| * the <a href="#name">binary name</a> of the class specified by |
| * the byte array {@code b}. |
| * Other properties of the defined package are as specified by {@link Package}. |
| * |
| * @param name |
| * The expected <a href="#name">binary name</a> of the class, or |
| * {@code null} if not known |
| * |
| * @param b |
| * The bytes that make up the class data. The bytes in positions |
| * {@code off} through {@code off+len-1} should have the format |
| * of a valid class file as defined by |
| * <cite>The Java™ Virtual Machine Specification</cite>. |
| * |
| * @param off |
| * The start offset in {@code b} of the class data |
| * |
| * @param len |
| * The length of the class data |
| * |
| * @param protectionDomain |
| * The {@code ProtectionDomain} of the class |
| * |
| * @return The {@code Class} object created from the data, |
| * and {@code ProtectionDomain}. |
| * |
| * @throws ClassFormatError |
| * If the data did not contain a valid class |
| * |
| * @throws NoClassDefFoundError |
| * If {@code name} is not {@code null} and not equal to the |
| * <a href="#name">binary name</a> of the class specified by {@code b} |
| * |
| * @throws IndexOutOfBoundsException |
| * If either {@code off} or {@code len} is negative, or if |
| * {@code off+len} is greater than {@code b.length}. |
| * |
| * @throws SecurityException |
| * If an attempt is made to add this class to a package that |
| * contains classes that were signed by a different set of |
| * certificates than this class, or if {@code name} begins with |
| * "{@code java.}" and this class loader is not the platform |
| * class loader or its ancestor. |
| * |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected final Class<?> defineClass(String name, byte[] b, int off, int len, |
| ProtectionDomain protectionDomain) |
| throws ClassFormatError |
| { |
| protectionDomain = preDefineClass(name, protectionDomain); |
| String source = defineClassSourceLocation(protectionDomain); |
| Class<?> c = defineClass1(this, name, b, off, len, protectionDomain, source); |
| postDefineClass(c, protectionDomain); |
| return c; |
| } |
| |
| /** |
| * Converts a {@link java.nio.ByteBuffer ByteBuffer} into an instance |
| * of class {@code Class}, with the given {@code ProtectionDomain}. |
| * If the given {@code ProtectionDomain} is {@code null}, then a default |
| * protection domain will be assigned to the class as |
| * specified in the documentation for {@link #defineClass(String, byte[], |
| * int, int)}. Before the class can be used it must be resolved. |
| * |
| * <p>The rules about the first class defined in a package determining the |
| * set of certificates for the package, the restrictions on class names, |
| * and the defined package of the class |
| * are identical to those specified in the documentation for {@link |
| * #defineClass(String, byte[], int, int, ProtectionDomain)}. |
| * |
| * <p> An invocation of this method of the form |
| * <i>cl</i>{@code .defineClass(}<i>name</i>{@code ,} |
| * <i>bBuffer</i>{@code ,} <i>pd</i>{@code )} yields exactly the same |
| * result as the statements |
| * |
| *<p> <code> |
| * ...<br> |
| * byte[] temp = new byte[bBuffer.{@link |
| * java.nio.ByteBuffer#remaining remaining}()];<br> |
| * bBuffer.{@link java.nio.ByteBuffer#get(byte[]) |
| * get}(temp);<br> |
| * return {@link #defineClass(String, byte[], int, int, ProtectionDomain) |
| * cl.defineClass}(name, temp, 0, |
| * temp.length, pd);<br> |
| * </code></p> |
| * |
| * @param name |
| * The expected <a href="#name">binary name</a>. of the class, or |
| * {@code null} if not known |
| * |
| * @param b |
| * The bytes that make up the class data. The bytes from positions |
| * {@code b.position()} through {@code b.position() + b.limit() -1 |
| * } should have the format of a valid class file as defined by |
| * <cite>The Java™ Virtual Machine Specification</cite>. |
| * |
| * @param protectionDomain |
| * The {@code ProtectionDomain} of the class, or {@code null}. |
| * |
| * @return The {@code Class} object created from the data, |
| * and {@code ProtectionDomain}. |
| * |
| * @throws ClassFormatError |
| * If the data did not contain a valid class. |
| * |
| * @throws NoClassDefFoundError |
| * If {@code name} is not {@code null} and not equal to the |
| * <a href="#name">binary name</a> of the class specified by {@code b} |
| * |
| * @throws SecurityException |
| * If an attempt is made to add this class to a package that |
| * contains classes that were signed by a different set of |
| * certificates than this class, or if {@code name} begins with |
| * "{@code java.}". |
| * |
| * @see #defineClass(String, byte[], int, int, ProtectionDomain) |
| * |
| * @since 1.5 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected final Class<?> defineClass(String name, java.nio.ByteBuffer b, |
| ProtectionDomain protectionDomain) |
| throws ClassFormatError |
| { |
| int len = b.remaining(); |
| |
| // Use byte[] if not a direct ByteBuffer: |
| if (!b.isDirect()) { |
| if (b.hasArray()) { |
| return defineClass(name, b.array(), |
| b.position() + b.arrayOffset(), len, |
| protectionDomain); |
| } else { |
| // no array, or read-only array |
| byte[] tb = new byte[len]; |
| b.get(tb); // get bytes out of byte buffer. |
| return defineClass(name, tb, 0, len, protectionDomain); |
| } |
| } |
| |
| protectionDomain = preDefineClass(name, protectionDomain); |
| String source = defineClassSourceLocation(protectionDomain); |
| Class<?> c = defineClass2(this, name, b, b.position(), len, protectionDomain, source); |
| postDefineClass(c, protectionDomain); |
| return c; |
| } |
| |
| static native Class<?> defineClass1(ClassLoader loader, String name, byte[] b, int off, int len, |
| ProtectionDomain pd, String source); |
| |
| static native Class<?> defineClass2(ClassLoader loader, String name, java.nio.ByteBuffer b, |
| int off, int len, ProtectionDomain pd, |
| String source); |
| |
| // true if the name is null or has the potential to be a valid binary name |
| private boolean checkName(String name) { |
| if ((name == null) || (name.length() == 0)) |
| return true; |
| if ((name.indexOf('/') != -1) || (name.charAt(0) == '[')) |
| return false; |
| return true; |
| } |
| |
| private void checkCerts(String name, CodeSource cs) { |
| int i = name.lastIndexOf('.'); |
| String pname = (i == -1) ? "" : name.substring(0, i); |
| |
| Certificate[] certs = null; |
| if (cs != null) { |
| certs = cs.getCertificates(); |
| } |
| Certificate[] pcerts = null; |
| if (parallelLockMap == null) { |
| synchronized (this) { |
| pcerts = package2certs.get(pname); |
| if (pcerts == null) { |
| package2certs.put(pname, (certs == null? nocerts:certs)); |
| } |
| } |
| } else { |
| pcerts = ((ConcurrentHashMap<String, Certificate[]>)package2certs). |
| putIfAbsent(pname, (certs == null? nocerts:certs)); |
| } |
| if (pcerts != null && !compareCerts(pcerts, certs)) { |
| throw new SecurityException("class \"" + name |
| + "\"'s signer information does not match signer information" |
| + " of other classes in the same package"); |
| } |
| } |
| |
| /** |
| * check to make sure the certs for the new class (certs) are the same as |
| * the certs for the first class inserted in the package (pcerts) |
| */ |
| private boolean compareCerts(Certificate[] pcerts, |
| Certificate[] certs) |
| { |
| // certs can be null, indicating no certs. |
| if ((certs == null) || (certs.length == 0)) { |
| return pcerts.length == 0; |
| } |
| |
| // the length must be the same at this point |
| if (certs.length != pcerts.length) |
| return false; |
| |
| // go through and make sure all the certs in one array |
| // are in the other and vice-versa. |
| boolean match; |
| for (Certificate cert : certs) { |
| match = false; |
| for (Certificate pcert : pcerts) { |
| if (cert.equals(pcert)) { |
| match = true; |
| break; |
| } |
| } |
| if (!match) return false; |
| } |
| |
| // now do the same for pcerts |
| for (Certificate pcert : pcerts) { |
| match = false; |
| for (Certificate cert : certs) { |
| if (pcert.equals(cert)) { |
| match = true; |
| break; |
| } |
| } |
| if (!match) return false; |
| } |
| |
| return true; |
| } |
| |
| /** |
| * Links the specified class. This (misleadingly named) method may be |
| * used by a class loader to link a class. If the class {@code c} has |
| * already been linked, then this method simply returns. Otherwise, the |
| * class is linked as described in the "Execution" chapter of |
| * <cite>The Java™ Language Specification</cite>. |
| * |
| * @param c |
| * The class to link |
| * |
| * @throws NullPointerException |
| * If {@code c} is {@code null}. |
| * |
| * @see #defineClass(String, byte[], int, int) |
| */ |
| protected final void resolveClass(Class<?> c) { |
| if (c == null) { |
| throw new NullPointerException(); |
| } |
| } |
| |
| /** |
| * Finds a class with the specified <a href="#name">binary name</a>, |
| * loading it if necessary. |
| * |
| * <p> This method loads the class through the system class loader (see |
| * {@link #getSystemClassLoader()}). The {@code Class} object returned |
| * might have more than one {@code ClassLoader} associated with it. |
| * Subclasses of {@code ClassLoader} need not usually invoke this method, |
| * because most class loaders need to override just {@link |
| * #findClass(String)}. </p> |
| * |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The {@code Class} object for the specified {@code name} |
| * |
| * @throws ClassNotFoundException |
| * If the class could not be found |
| * |
| * @see #ClassLoader(ClassLoader) |
| * @see #getParent() |
| */ |
| protected final Class<?> findSystemClass(String name) |
| throws ClassNotFoundException |
| { |
| return getSystemClassLoader().loadClass(name); |
| } |
| |
| /** |
| * Returns a class loaded by the bootstrap class loader; |
| * or return null if not found. |
| */ |
| Class<?> findBootstrapClassOrNull(String name) { |
| if (!checkName(name)) return null; |
| |
| return findBootstrapClass(name); |
| } |
| |
| // return null if not found |
| private native Class<?> findBootstrapClass(String name); |
| |
| /** |
| * Returns the class with the given <a href="#name">binary name</a> if this |
| * loader has been recorded by the Java virtual machine as an initiating |
| * loader of a class with that <a href="#name">binary name</a>. Otherwise |
| * {@code null} is returned. |
| * |
| * @param name |
| * The <a href="#name">binary name</a> of the class |
| * |
| * @return The {@code Class} object, or {@code null} if the class has |
| * not been loaded |
| * |
| * @since 1.1 |
| */ |
| protected final Class<?> findLoadedClass(String name) { |
| if (!checkName(name)) |
| return null; |
| return findLoadedClass0(name); |
| } |
| |
| private final native Class<?> findLoadedClass0(String name); |
| |
| /** |
| * Sets the signers of a class. This should be invoked after defining a |
| * class. |
| * |
| * @param c |
| * The {@code Class} object |
| * |
| * @param signers |
| * The signers for the class |
| * |
| * @since 1.1 |
| */ |
| protected final void setSigners(Class<?> c, Object[] signers) { |
| c.setSigners(signers); |
| } |
| |
| |
| // -- Resources -- |
| |
| /** |
| * Returns a URL to a resource in a module defined to this class loader. |
| * Class loader implementations that support the loading from modules |
| * should override this method. |
| * |
| * @apiNote This method is the basis for the {@link |
| * Class#getResource Class.getResource}, {@link Class#getResourceAsStream |
| * Class.getResourceAsStream}, and {@link Module#getResourceAsStream |
| * Module.getResourceAsStream} methods. It is not subject to the rules for |
| * encapsulation specified by {@code Module.getResourceAsStream}. |
| * |
| * @implSpec The default implementation attempts to find the resource by |
| * invoking {@link #findResource(String)} when the {@code moduleName} is |
| * {@code null}. It otherwise returns {@code null}. |
| * |
| * @param moduleName |
| * The module name; or {@code null} to find a resource in the |
| * {@linkplain #getUnnamedModule() unnamed module} for this |
| * class loader |
| * @param name |
| * The resource name |
| * |
| * @return A URL to the resource; {@code null} if the resource could not be |
| * found, a URL could not be constructed to locate the resource, |
| * access to the resource is denied by the security manager, or |
| * there isn't a module of the given name defined to the class |
| * loader. |
| * |
| * @throws IOException |
| * If I/O errors occur |
| * |
| * @see java.lang.module.ModuleReader#find(String) |
| * @since 9 |
| * @spec JPMS |
| */ |
| protected URL findResource(String moduleName, String name) throws IOException { |
| if (moduleName == null) { |
| return findResource(name); |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * Finds the resource with the given name. A resource is some data |
| * (images, audio, text, etc) that can be accessed by class code in a way |
| * that is independent of the location of the code. |
| * |
| * <p> The name of a resource is a '{@code /}'-separated path name that |
| * identifies the resource. </p> |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally (even if the caller of this method is in the |
| * same module as the resource). </p> |
| * |
| * @implSpec The default implementation will first search the parent class |
| * loader for the resource; if the parent is {@code null} the path of the |
| * class loader built into the virtual machine is searched. If not found, |
| * this method will invoke {@link #findResource(String)} to find the resource. |
| * |
| * @apiNote Where several modules are defined to the same class loader, |
| * and where more than one module contains a resource with the given name, |
| * then the ordering that modules are searched is not specified and may be |
| * very unpredictable. |
| * When overriding this method it is recommended that an implementation |
| * ensures that any delegation is consistent with the {@link |
| * #getResources(java.lang.String) getResources(String)} method. |
| * |
| * @param name |
| * The resource name |
| * |
| * @return {@code URL} object for reading the resource; {@code null} if |
| * the resource could not be found, a {@code URL} could not be |
| * constructed to locate the resource, the resource is in a package |
| * that is not opened unconditionally, or access to the resource is |
| * denied by the security manager. |
| * |
| * @throws NullPointerException If {@code name} is {@code null} |
| * |
| * @since 1.1 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public URL getResource(String name) { |
| Objects.requireNonNull(name); |
| URL url; |
| if (parent != null) { |
| url = parent.getResource(name); |
| } else { |
| url = BootLoader.findResource(name); |
| } |
| if (url == null) { |
| url = findResource(name); |
| } |
| return url; |
| } |
| |
| /** |
| * Finds all the resources with the given name. A resource is some data |
| * (images, audio, text, etc) that can be accessed by class code in a way |
| * that is independent of the location of the code. |
| * |
| * <p> The name of a resource is a {@code /}-separated path name that |
| * identifies the resource. </p> |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally (even if the caller of this method is in the |
| * same module as the resource). </p> |
| * |
| * @implSpec The default implementation will first search the parent class |
| * loader for the resource; if the parent is {@code null} the path of the |
| * class loader built into the virtual machine is searched. It then |
| * invokes {@link #findResources(String)} to find the resources with the |
| * name in this class loader. It returns an enumeration whose elements |
| * are the URLs found by searching the parent class loader followed by |
| * the elements found with {@code findResources}. |
| * |
| * @apiNote Where several modules are defined to the same class loader, |
| * and where more than one module contains a resource with the given name, |
| * then the ordering is not specified and may be very unpredictable. |
| * When overriding this method it is recommended that an |
| * implementation ensures that any delegation is consistent with the {@link |
| * #getResource(java.lang.String) getResource(String)} method. This should |
| * ensure that the first element returned by the Enumeration's |
| * {@code nextElement} method is the same resource that the |
| * {@code getResource(String)} method would return. |
| * |
| * @param name |
| * The resource name |
| * |
| * @return An enumeration of {@link java.net.URL URL} objects for |
| * the resource. If no resources could be found, the enumeration |
| * will be empty. Resources for which a {@code URL} cannot be |
| * constructed, are in package that is not opened unconditionally, |
| * or access to the resource is denied by the security manager, |
| * are not returned in the enumeration. |
| * |
| * @throws IOException |
| * If I/O errors occur |
| * @throws NullPointerException If {@code name} is {@code null} |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public Enumeration<URL> getResources(String name) throws IOException { |
| Objects.requireNonNull(name); |
| @SuppressWarnings("unchecked") |
| Enumeration<URL>[] tmp = (Enumeration<URL>[]) new Enumeration<?>[2]; |
| if (parent != null) { |
| tmp[0] = parent.getResources(name); |
| } else { |
| tmp[0] = BootLoader.findResources(name); |
| } |
| tmp[1] = findResources(name); |
| |
| return new CompoundEnumeration<>(tmp); |
| } |
| |
| /** |
| * Returns a stream whose elements are the URLs of all the resources with |
| * the given name. A resource is some data (images, audio, text, etc) that |
| * can be accessed by class code in a way that is independent of the |
| * location of the code. |
| * |
| * <p> The name of a resource is a {@code /}-separated path name that |
| * identifies the resource. |
| * |
| * <p> The resources will be located when the returned stream is evaluated. |
| * If the evaluation results in an {@code IOException} then the I/O |
| * exception is wrapped in an {@link UncheckedIOException} that is then |
| * thrown. |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally (even if the caller of this method is in the |
| * same module as the resource). </p> |
| * |
| * @implSpec The default implementation invokes {@link #getResources(String) |
| * getResources} to find all the resources with the given name and returns |
| * a stream with the elements in the enumeration as the source. |
| * |
| * @apiNote When overriding this method it is recommended that an |
| * implementation ensures that any delegation is consistent with the {@link |
| * #getResource(java.lang.String) getResource(String)} method. This should |
| * ensure that the first element returned by the stream is the same |
| * resource that the {@code getResource(String)} method would return. |
| * |
| * @param name |
| * The resource name |
| * |
| * @return A stream of resource {@link java.net.URL URL} objects. If no |
| * resources could be found, the stream will be empty. Resources |
| * for which a {@code URL} cannot be constructed, are in a package |
| * that is not opened unconditionally, or access to the resource |
| * is denied by the security manager, will not be in the stream. |
| * |
| * @throws NullPointerException If {@code name} is {@code null} |
| * |
| * @since 9 |
| */ |
| public Stream<URL> resources(String name) { |
| Objects.requireNonNull(name); |
| int characteristics = Spliterator.NONNULL | Spliterator.IMMUTABLE; |
| Supplier<Spliterator<URL>> si = () -> { |
| try { |
| return Spliterators.spliteratorUnknownSize( |
| getResources(name).asIterator(), characteristics); |
| } catch (IOException e) { |
| throw new UncheckedIOException(e); |
| } |
| }; |
| return StreamSupport.stream(si, characteristics, false); |
| } |
| |
| /** |
| * Finds the resource with the given name. Class loader implementations |
| * should override this method. |
| * |
| * <p> For resources in named modules then the method must implement the |
| * rules for encapsulation specified in the {@code Module} {@link |
| * Module#getResourceAsStream getResourceAsStream} method. Additionally, |
| * it must not find non-"{@code .class}" resources in packages of named |
| * modules unless the package is {@link Module#isOpen(String) opened} |
| * unconditionally. </p> |
| * |
| * @implSpec The default implementation returns {@code null}. |
| * |
| * @param name |
| * The resource name |
| * |
| * @return {@code URL} object for reading the resource; {@code null} if |
| * the resource could not be found, a {@code URL} could not be |
| * constructed to locate the resource, the resource is in a package |
| * that is not opened unconditionally, or access to the resource is |
| * denied by the security manager. |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected URL findResource(String name) { |
| return null; |
| } |
| |
| /** |
| * Returns an enumeration of {@link java.net.URL URL} objects |
| * representing all the resources with the given name. Class loader |
| * implementations should override this method. |
| * |
| * <p> For resources in named modules then the method must implement the |
| * rules for encapsulation specified in the {@code Module} {@link |
| * Module#getResourceAsStream getResourceAsStream} method. Additionally, |
| * it must not find non-"{@code .class}" resources in packages of named |
| * modules unless the package is {@link Module#isOpen(String) opened} |
| * unconditionally. </p> |
| * |
| * @implSpec The default implementation returns an enumeration that |
| * contains no elements. |
| * |
| * @param name |
| * The resource name |
| * |
| * @return An enumeration of {@link java.net.URL URL} objects for |
| * the resource. If no resources could be found, the enumeration |
| * will be empty. Resources for which a {@code URL} cannot be |
| * constructed, are in a package that is not opened unconditionally, |
| * or access to the resource is denied by the security manager, |
| * are not returned in the enumeration. |
| * |
| * @throws IOException |
| * If I/O errors occur |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected Enumeration<URL> findResources(String name) throws IOException { |
| return Collections.emptyEnumeration(); |
| } |
| |
| /** |
| * Registers the caller as |
| * {@linkplain #isRegisteredAsParallelCapable() parallel capable}. |
| * The registration succeeds if and only if all of the following |
| * conditions are met: |
| * <ol> |
| * <li> no instance of the caller has been created</li> |
| * <li> all of the super classes (except class Object) of the caller are |
| * registered as parallel capable</li> |
| * </ol> |
| * <p>Note that once a class loader is registered as parallel capable, there |
| * is no way to change it back.</p> |
| * |
| * @return {@code true} if the caller is successfully registered as |
| * parallel capable and {@code false} if otherwise. |
| * |
| * @see #isRegisteredAsParallelCapable() |
| * |
| * @since 1.7 |
| */ |
| @CallerSensitive |
| protected static boolean registerAsParallelCapable() { |
| Class<? extends ClassLoader> callerClass = |
| Reflection.getCallerClass().asSubclass(ClassLoader.class); |
| return ParallelLoaders.register(callerClass); |
| } |
| |
| /** |
| * Returns {@code true} if this class loader is registered as |
| * {@linkplain #registerAsParallelCapable parallel capable}, otherwise |
| * {@code false}. |
| * |
| * @return {@code true} if this class loader is parallel capable, |
| * otherwise {@code false}. |
| * |
| * @see #registerAsParallelCapable() |
| * |
| * @since 9 |
| */ |
| public final boolean isRegisteredAsParallelCapable() { |
| return ParallelLoaders.isRegistered(this.getClass()); |
| } |
| |
| /** |
| * Find a resource of the specified name from the search path used to load |
| * classes. This method locates the resource through the system class |
| * loader (see {@link #getSystemClassLoader()}). |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally. </p> |
| * |
| * @param name |
| * The resource name |
| * |
| * @return A {@link java.net.URL URL} to the resource; {@code |
| * null} if the resource could not be found, a URL could not be |
| * constructed to locate the resource, the resource is in a package |
| * that is not opened unconditionally or access to the resource is |
| * denied by the security manager. |
| * |
| * @since 1.1 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public static URL getSystemResource(String name) { |
| return getSystemClassLoader().getResource(name); |
| } |
| |
| /** |
| * Finds all resources of the specified name from the search path used to |
| * load classes. The resources thus found are returned as an |
| * {@link java.util.Enumeration Enumeration} of {@link |
| * java.net.URL URL} objects. |
| * |
| * <p> The search order is described in the documentation for {@link |
| * #getSystemResource(String)}. </p> |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally. </p> |
| * |
| * @param name |
| * The resource name |
| * |
| * @return An enumeration of {@link java.net.URL URL} objects for |
| * the resource. If no resources could be found, the enumeration |
| * will be empty. Resources for which a {@code URL} cannot be |
| * constructed, are in a package that is not opened unconditionally, |
| * or access to the resource is denied by the security manager, |
| * are not returned in the enumeration. |
| * |
| * @throws IOException |
| * If I/O errors occur |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public static Enumeration<URL> getSystemResources(String name) |
| throws IOException |
| { |
| return getSystemClassLoader().getResources(name); |
| } |
| |
| /** |
| * Returns an input stream for reading the specified resource. |
| * |
| * <p> The search order is described in the documentation for {@link |
| * #getResource(String)}. </p> |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally. </p> |
| * |
| * @param name |
| * The resource name |
| * |
| * @return An input stream for reading the resource; {@code null} if the |
| * resource could not be found, the resource is in a package that |
| * is not opened unconditionally, or access to the resource is |
| * denied by the security manager. |
| * |
| * @throws NullPointerException If {@code name} is {@code null} |
| * |
| * @since 1.1 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public InputStream getResourceAsStream(String name) { |
| Objects.requireNonNull(name); |
| URL url = getResource(name); |
| try { |
| return url != null ? url.openStream() : null; |
| } catch (IOException e) { |
| return null; |
| } |
| } |
| |
| /** |
| * Open for reading, a resource of the specified name from the search path |
| * used to load classes. This method locates the resource through the |
| * system class loader (see {@link #getSystemClassLoader()}). |
| * |
| * <p> Resources in named modules are subject to the encapsulation rules |
| * specified by {@link Module#getResourceAsStream Module.getResourceAsStream}. |
| * Additionally, and except for the special case where the resource has a |
| * name ending with "{@code .class}", this method will only find resources in |
| * packages of named modules when the package is {@link Module#isOpen(String) |
| * opened} unconditionally. </p> |
| * |
| * @param name |
| * The resource name |
| * |
| * @return An input stream for reading the resource; {@code null} if the |
| * resource could not be found, the resource is in a package that |
| * is not opened unconditionally, or access to the resource is |
| * denied by the security manager. |
| * |
| * @since 1.1 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| public static InputStream getSystemResourceAsStream(String name) { |
| URL url = getSystemResource(name); |
| try { |
| return url != null ? url.openStream() : null; |
| } catch (IOException e) { |
| return null; |
| } |
| } |
| |
| |
| // -- Hierarchy -- |
| |
| /** |
| * Returns the parent class loader for delegation. Some implementations may |
| * use {@code null} to represent the bootstrap class loader. This method |
| * will return {@code null} in such implementations if this class loader's |
| * parent is the bootstrap class loader. |
| * |
| * @return The parent {@code ClassLoader} |
| * |
| * @throws SecurityException |
| * If a security manager is present, and the caller's class loader |
| * is not {@code null} and is not an ancestor of this class loader, |
| * and the caller does not have the |
| * {@link RuntimePermission}{@code ("getClassLoader")} |
| * |
| * @since 1.2 |
| */ |
| @CallerSensitive |
| public final ClassLoader getParent() { |
| if (parent == null) |
| return null; |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| // Check access to the parent class loader |
| // If the caller's class loader is same as this class loader, |
| // permission check is performed. |
| checkClassLoaderPermission(parent, Reflection.getCallerClass()); |
| } |
| return parent; |
| } |
| |
| /** |
| * Returns the unnamed {@code Module} for this class loader. |
| * |
| * @return The unnamed Module for this class loader |
| * |
| * @see Module#isNamed() |
| * @since 9 |
| * @spec JPMS |
| */ |
| public final Module getUnnamedModule() { |
| return unnamedModule; |
| } |
| |
| /** |
| * Returns the platform class loader for delegation. All |
| * <a href="#builtinLoaders">platform classes</a> are visible to |
| * the platform class loader. |
| * |
| * @implNote The name of the builtin platform class loader is |
| * {@code "platform"}. |
| * |
| * @return The platform {@code ClassLoader}. |
| * |
| * @throws SecurityException |
| * If a security manager is present, and the caller's class loader is |
| * not {@code null}, and the caller's class loader is not the same |
| * as or an ancestor of the platform class loader, |
| * and the caller does not have the |
| * {@link RuntimePermission}{@code ("getClassLoader")} |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| @CallerSensitive |
| public static ClassLoader getPlatformClassLoader() { |
| SecurityManager sm = System.getSecurityManager(); |
| ClassLoader loader = getBuiltinPlatformClassLoader(); |
| if (sm != null) { |
| checkClassLoaderPermission(loader, Reflection.getCallerClass()); |
| } |
| return loader; |
| } |
| |
| /** |
| * Returns the system class loader for delegation. This is the default |
| * delegation parent for new {@code ClassLoader} instances, and is |
| * typically the class loader used to start the application. |
| * |
| * <p> This method is first invoked early in the runtime's startup |
| * sequence, at which point it creates the system class loader. This |
| * class loader will be the context class loader for the main application |
| * thread (for example, the thread that invokes the {@code main} method of |
| * the main class). |
| * |
| * <p> The default system class loader is an implementation-dependent |
| * instance of this class. |
| * |
| * <p> If the system property "{@code java.system.class.loader}" is defined |
| * when this method is first invoked then the value of that property is |
| * taken to be the name of a class that will be returned as the system |
| * class loader. The class is loaded using the default system class loader |
| * and must define a public constructor that takes a single parameter of |
| * type {@code ClassLoader} which is used as the delegation parent. An |
| * instance is then created using this constructor with the default system |
| * class loader as the parameter. The resulting class loader is defined |
| * to be the system class loader. During construction, the class loader |
| * should take great care to avoid calling {@code getSystemClassLoader()}. |
| * If circular initialization of the system class loader is detected then |
| * an unspecified error or exception is thrown. |
| * |
| * @implNote The system property to override the system class loader is not |
| * examined until the VM is almost fully initialized. Code that executes |
| * this method during startup should take care not to cache the return |
| * value until the system is fully initialized. |
| * |
| * <p> The name of the built-in system class loader is {@code "app"}. |
| * The class path used by the built-in system class loader is determined |
| * by the system property "{@code java.class.path}" during early |
| * initialization of the VM. If the system property is not defined, |
| * or its value is an empty string, then there is no class path |
| * when the initial module is a module on the application module path, |
| * i.e. <em>a named module</em>. If the initial module is not on |
| * the application module path then the class path defaults to |
| * the current working directory. |
| * |
| * @return The system {@code ClassLoader} for delegation |
| * |
| * @throws SecurityException |
| * If a security manager is present, and the caller's class loader |
| * is not {@code null} and is not the same as or an ancestor of the |
| * system class loader, and the caller does not have the |
| * {@link RuntimePermission}{@code ("getClassLoader")} |
| * |
| * @throws IllegalStateException |
| * If invoked recursively during the construction of the class |
| * loader specified by the "{@code java.system.class.loader}" |
| * property. |
| * |
| * @throws Error |
| * If the system property "{@code java.system.class.loader}" |
| * is defined but the named class could not be loaded, the |
| * provider class does not define the required constructor, or an |
| * exception is thrown by that constructor when it is invoked. The |
| * underlying cause of the error can be retrieved via the |
| * {@link Throwable#getCause()} method. |
| * |
| * @revised 1.4 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| @CallerSensitive |
| public static ClassLoader getSystemClassLoader() { |
| switch (VM.initLevel()) { |
| case 0: |
| case 1: |
| case 2: |
| // the system class loader is the built-in app class loader during startup |
| return getBuiltinAppClassLoader(); |
| case 3: |
| String msg = "getSystemClassLoader should only be called after VM booted"; |
| throw new InternalError(msg); |
| case 4: |
| // system fully initialized |
| assert VM.isBooted() && scl != null; |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| checkClassLoaderPermission(scl, Reflection.getCallerClass()); |
| } |
| return scl; |
| default: |
| throw new InternalError("should not reach here"); |
| } |
| } |
| |
| static ClassLoader getBuiltinPlatformClassLoader() { |
| return ClassLoaders.platformClassLoader(); |
| } |
| |
| static ClassLoader getBuiltinAppClassLoader() { |
| return ClassLoaders.appClassLoader(); |
| } |
| |
| /* |
| * Initialize the system class loader that may be a custom class on the |
| * application class path or application module path. |
| * |
| * @see java.lang.System#initPhase3 |
| */ |
| static synchronized ClassLoader initSystemClassLoader() { |
| if (VM.initLevel() != 3) { |
| throw new InternalError("system class loader cannot be set at initLevel " + |
| VM.initLevel()); |
| } |
| |
| // detect recursive initialization |
| if (scl != null) { |
| throw new IllegalStateException("recursive invocation"); |
| } |
| |
| ClassLoader builtinLoader = getBuiltinAppClassLoader(); |
| |
| // All are privileged frames. No need to call doPrivileged. |
| String cn = System.getProperty("java.system.class.loader"); |
| if (cn != null) { |
| try { |
| // custom class loader is only supported to be loaded from unnamed module |
| Constructor<?> ctor = Class.forName(cn, false, builtinLoader) |
| .getDeclaredConstructor(ClassLoader.class); |
| scl = (ClassLoader) ctor.newInstance(builtinLoader); |
| } catch (Exception e) { |
| throw new Error(e); |
| } |
| } else { |
| scl = builtinLoader; |
| } |
| return scl; |
| } |
| |
| // Returns true if the specified class loader can be found in this class |
| // loader's delegation chain. |
| boolean isAncestor(ClassLoader cl) { |
| ClassLoader acl = this; |
| do { |
| acl = acl.parent; |
| if (cl == acl) { |
| return true; |
| } |
| } while (acl != null); |
| return false; |
| } |
| |
| // Tests if class loader access requires "getClassLoader" permission |
| // check. A class loader 'from' can access class loader 'to' if |
| // class loader 'from' is same as class loader 'to' or an ancestor |
| // of 'to'. The class loader in a system domain can access |
| // any class loader. |
| private static boolean needsClassLoaderPermissionCheck(ClassLoader from, |
| ClassLoader to) |
| { |
| if (from == to) |
| return false; |
| |
| if (from == null) |
| return false; |
| |
| return !to.isAncestor(from); |
| } |
| |
| // Returns the class's class loader, or null if none. |
| static ClassLoader getClassLoader(Class<?> caller) { |
| // This can be null if the VM is requesting it |
| if (caller == null) { |
| return null; |
| } |
| // Circumvent security check since this is package-private |
| return caller.getClassLoader0(); |
| } |
| |
| /* |
| * Checks RuntimePermission("getClassLoader") permission |
| * if caller's class loader is not null and caller's class loader |
| * is not the same as or an ancestor of the given cl argument. |
| */ |
| static void checkClassLoaderPermission(ClassLoader cl, Class<?> caller) { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| // caller can be null if the VM is requesting it |
| ClassLoader ccl = getClassLoader(caller); |
| if (needsClassLoaderPermissionCheck(ccl, cl)) { |
| sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); |
| } |
| } |
| } |
| |
| // The system class loader |
| // @GuardedBy("ClassLoader.class") |
| private static volatile ClassLoader scl; |
| |
| // -- Package -- |
| |
| /** |
| * Define a Package of the given Class object. |
| * |
| * If the given class represents an array type, a primitive type or void, |
| * this method returns {@code null}. |
| * |
| * This method does not throw IllegalArgumentException. |
| */ |
| Package definePackage(Class<?> c) { |
| if (c.isPrimitive() || c.isArray()) { |
| return null; |
| } |
| |
| return definePackage(c.getPackageName(), c.getModule()); |
| } |
| |
| /** |
| * Defines a Package of the given name and module |
| * |
| * This method does not throw IllegalArgumentException. |
| * |
| * @param name package name |
| * @param m module |
| */ |
| Package definePackage(String name, Module m) { |
| if (name.isEmpty() && m.isNamed()) { |
| throw new InternalError("unnamed package in " + m); |
| } |
| |
| // check if Package object is already defined |
| NamedPackage pkg = packages.get(name); |
| if (pkg instanceof Package) |
| return (Package)pkg; |
| |
| return (Package)packages.compute(name, (n, p) -> toPackage(n, p, m)); |
| } |
| |
| /* |
| * Returns a Package object for the named package |
| */ |
| private Package toPackage(String name, NamedPackage p, Module m) { |
| // define Package object if the named package is not yet defined |
| if (p == null) |
| return NamedPackage.toPackage(name, m); |
| |
| // otherwise, replace the NamedPackage object with Package object |
| if (p instanceof Package) |
| return (Package)p; |
| |
| return NamedPackage.toPackage(p.packageName(), p.module()); |
| } |
| |
| /** |
| * Defines a package by <a href="#name">name</a> in this {@code ClassLoader}. |
| * <p> |
| * <a href="#name">Package names</a> must be unique within a class loader and |
| * cannot be redefined or changed once created. |
| * <p> |
| * If a class loader wishes to define a package with specific properties, |
| * such as version information, then the class loader should call this |
| * {@code definePackage} method before calling {@code defineClass}. |
| * Otherwise, the |
| * {@link #defineClass(String, byte[], int, int, ProtectionDomain) defineClass} |
| * method will define a package in this class loader corresponding to the package |
| * of the newly defined class; the properties of this defined package are |
| * specified by {@link Package}. |
| * |
| * @apiNote |
| * A class loader that wishes to define a package for classes in a JAR |
| * typically uses the specification and implementation titles, versions, and |
| * vendors from the JAR's manifest. If the package is specified as |
| * {@linkplain java.util.jar.Attributes.Name#SEALED sealed} in the JAR's manifest, |
| * the {@code URL} of the JAR file is typically used as the {@code sealBase}. |
| * If classes of package {@code 'p'} defined by this class loader |
| * are loaded from multiple JARs, the {@code Package} object may contain |
| * different information depending on the first class of package {@code 'p'} |
| * defined and which JAR's manifest is read first to explicitly define |
| * package {@code 'p'}. |
| * |
| * <p> It is strongly recommended that a class loader does not call this |
| * method to explicitly define packages in <em>named modules</em>; instead, |
| * the package will be automatically defined when a class is {@linkplain |
| * #defineClass(String, byte[], int, int, ProtectionDomain) being defined}. |
| * If it is desirable to define {@code Package} explicitly, it should ensure |
| * that all packages in a named module are defined with the properties |
| * specified by {@link Package}. Otherwise, some {@code Package} objects |
| * in a named module may be for example sealed with different seal base. |
| * |
| * @param name |
| * The <a href="#name">package name</a> |
| * |
| * @param specTitle |
| * The specification title |
| * |
| * @param specVersion |
| * The specification version |
| * |
| * @param specVendor |
| * The specification vendor |
| * |
| * @param implTitle |
| * The implementation title |
| * |
| * @param implVersion |
| * The implementation version |
| * |
| * @param implVendor |
| * The implementation vendor |
| * |
| * @param sealBase |
| * If not {@code null}, then this package is sealed with |
| * respect to the given code source {@link java.net.URL URL} |
| * object. Otherwise, the package is not sealed. |
| * |
| * @return The newly defined {@code Package} object |
| * |
| * @throws NullPointerException |
| * if {@code name} is {@code null}. |
| * |
| * @throws IllegalArgumentException |
| * if a package of the given {@code name} is already |
| * defined by this class loader |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| * |
| * @see <a href="{@docRoot}/../specs/jar/jar.html#sealing"> |
| * The JAR File Specification: Package Sealing</a> |
| */ |
| protected Package definePackage(String name, String specTitle, |
| String specVersion, String specVendor, |
| String implTitle, String implVersion, |
| String implVendor, URL sealBase) |
| { |
| Objects.requireNonNull(name); |
| |
| // definePackage is not final and may be overridden by custom class loader |
| Package p = new Package(name, specTitle, specVersion, specVendor, |
| implTitle, implVersion, implVendor, |
| sealBase, this); |
| |
| if (packages.putIfAbsent(name, p) != null) |
| throw new IllegalArgumentException(name); |
| |
| return p; |
| } |
| |
| /** |
| * Returns a {@code Package} of the given <a href="#name">name</a> that has been |
| * defined by this class loader. |
| * |
| * @param name The <a href="#name">package name</a> |
| * |
| * @return The {@code Package} of the given name defined by this class loader, |
| * or {@code null} if not found |
| * |
| * @throws NullPointerException |
| * if {@code name} is {@code null}. |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| public final Package getDefinedPackage(String name) { |
| Objects.requireNonNull(name, "name cannot be null"); |
| |
| NamedPackage p = packages.get(name); |
| if (p == null) |
| return null; |
| |
| return definePackage(name, p.module()); |
| } |
| |
| /** |
| * Returns all of the {@code Package}s defined by this class loader. |
| * The returned array has no duplicated {@code Package}s of the same name. |
| * |
| * @apiNote This method returns an array rather than a {@code Set} or {@code Stream} |
| * for consistency with the existing {@link #getPackages} method. |
| * |
| * @return The array of {@code Package} objects defined by this class loader; |
| * or an zero length array if no package has been defined by this class loader. |
| * |
| * @since 9 |
| * @spec JPMS |
| */ |
| public final Package[] getDefinedPackages() { |
| return packages().toArray(Package[]::new); |
| } |
| |
| /** |
| * Finds a package by <a href="#name">name</a> in this class loader and its ancestors. |
| * <p> |
| * If this class loader defines a {@code Package} of the given name, |
| * the {@code Package} is returned. Otherwise, the ancestors of |
| * this class loader are searched recursively (parent by parent) |
| * for a {@code Package} of the given name. |
| * |
| * @apiNote The {@link #getPlatformClassLoader() platform class loader} |
| * may delegate to the application class loader but the application class |
| * loader is not its ancestor. When invoked on the platform class loader, |
| * this method will not find packages defined to the application |
| * class loader. |
| * |
| * @param name |
| * The <a href="#name">package name</a> |
| * |
| * @return The {@code Package} corresponding to the given name defined by |
| * this class loader or its ancestors, or {@code null} if not found. |
| * |
| * @throws NullPointerException |
| * if {@code name} is {@code null}. |
| * |
| * @deprecated |
| * If multiple class loaders delegate to each other and define classes |
| * with the same package name, and one such loader relies on the lookup |
| * behavior of {@code getPackage} to return a {@code Package} from |
| * a parent loader, then the properties exposed by the {@code Package} |
| * may not be as expected in the rest of the program. |
| * For example, the {@code Package} will only expose annotations from the |
| * {@code package-info.class} file defined by the parent loader, even if |
| * annotations exist in a {@code package-info.class} file defined by |
| * a child loader. A more robust approach is to use the |
| * {@link ClassLoader#getDefinedPackage} method which returns |
| * a {@code Package} for the specified class loader. |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| @Deprecated(since="9") |
| protected Package getPackage(String name) { |
| Package pkg = getDefinedPackage(name); |
| if (pkg == null) { |
| if (parent != null) { |
| pkg = parent.getPackage(name); |
| } else { |
| pkg = BootLoader.getDefinedPackage(name); |
| } |
| } |
| return pkg; |
| } |
| |
| /** |
| * Returns all of the {@code Package}s defined by this class loader |
| * and its ancestors. The returned array may contain more than one |
| * {@code Package} object of the same package name, each defined by |
| * a different class loader in the class loader hierarchy. |
| * |
| * @apiNote The {@link #getPlatformClassLoader() platform class loader} |
| * may delegate to the application class loader. In other words, |
| * packages in modules defined to the application class loader may be |
| * visible to the platform class loader. On the other hand, |
| * the application class loader is not its ancestor and hence |
| * when invoked on the platform class loader, this method will not |
| * return any packages defined to the application class loader. |
| * |
| * @return The array of {@code Package} objects defined by this |
| * class loader and its ancestors |
| * |
| * @since 1.2 |
| * @revised 9 |
| * @spec JPMS |
| */ |
| protected Package[] getPackages() { |
| Stream<Package> pkgs = packages(); |
| ClassLoader ld = parent; |
| while (ld != null) { |
| pkgs = Stream.concat(ld.packages(), pkgs); |
| ld = ld.parent; |
| } |
| return Stream.concat(BootLoader.packages(), pkgs) |
| .toArray(Package[]::new); |
| } |
| |
| |
| |
| // package-private |
| |
| /** |
| * Returns a stream of Packages defined in this class loader |
| */ |
| Stream<Package> packages() { |
| return packages.values().stream() |
| .map(p -> definePackage(p.packageName(), p.module())); |
| } |
| |
| // -- Native library access -- |
| |
| /** |
| * Returns the absolute path name of a native library. The VM invokes this |
| * method to locate the native libraries that belong to classes loaded with |
| * this class loader. If this method returns {@code null}, the VM |
| * searches the library along the path specified as the |
| * "{@code java.library.path}" property. |
| * |
| * @param libname |
| * The library name |
| * |
| * @return The absolute path of the native library |
| * |
| * @see System#loadLibrary(String) |
| * @see System#mapLibraryName(String) |
| * |
| * @since 1.2 |
| */ |
| protected String findLibrary(String libname) { |
| return null; |
| } |
| |
| /** |
| * The inner class NativeLibrary denotes a loaded native library instance. |
| * Every classloader contains a vector of loaded native libraries in the |
| * private field {@code nativeLibraries}. The native libraries loaded |
| * into the system are entered into the {@code systemNativeLibraries} |
| * vector. |
| * |
| * <p> Every native library requires a particular version of JNI. This is |
| * denoted by the private {@code jniVersion} field. This field is set by |
| * the VM when it loads the library, and used by the VM to pass the correct |
| * version of JNI to the native methods. </p> |
| * |
| * @see ClassLoader |
| * @since 1.2 |
| */ |
| static class NativeLibrary { |
| // opaque handle to native library, used in native code. |
| long handle; |
| // the version of JNI environment the native library requires. |
| private int jniVersion; |
| // the class from which the library is loaded, also indicates |
| // the loader this native library belongs. |
| private final Class<?> fromClass; |
| // the canonicalized name of the native library. |
| // or static library name |
| String name; |
| // Indicates if the native library is linked into the VM |
| boolean isBuiltin; |
| // Indicates if the native library is loaded |
| boolean loaded; |
| native void load(String name, boolean isBuiltin); |
| |
| native long find(String name); |
| native void unload(String name, boolean isBuiltin); |
| |
| public NativeLibrary(Class<?> fromClass, String name, boolean isBuiltin) { |
| this.name = name; |
| this.fromClass = fromClass; |
| this.isBuiltin = isBuiltin; |
| } |
| |
| @SuppressWarnings("deprecation") |
| protected void finalize() { |
| synchronized (loadedLibraryNames) { |
| if (fromClass.getClassLoader() != null && loaded) { |
| /* remove the native library name */ |
| int size = loadedLibraryNames.size(); |
| for (int i = 0; i < size; i++) { |
| if (name.equals(loadedLibraryNames.elementAt(i))) { |
| loadedLibraryNames.removeElementAt(i); |
| break; |
| } |
| } |
| /* unload the library. */ |
| ClassLoader.nativeLibraryContext.push(this); |
| try { |
| unload(name, isBuiltin); |
| } finally { |
| ClassLoader.nativeLibraryContext.pop(); |
| } |
| } |
| } |
| } |
| // Invoked in the VM to determine the context class in |
| // JNI_Load/JNI_Unload |
| static Class<?> getFromClass() { |
| return ClassLoader.nativeLibraryContext.peek().fromClass; |
| } |
| } |
| |
| // All native library names we've loaded. |
| private static Vector<String> loadedLibraryNames = new Vector<>(); |
| |
| // Native libraries belonging to system classes. |
| private static Vector<NativeLibrary> systemNativeLibraries |
| = new Vector<>(); |
| |
| // Native libraries associated with the class loader. |
| private Vector<NativeLibrary> nativeLibraries = new Vector<>(); |
| |
| // native libraries being loaded/unloaded. |
| private static Stack<NativeLibrary> nativeLibraryContext = new Stack<>(); |
| |
| // The paths searched for libraries |
| private static String usr_paths[]; |
| private static String sys_paths[]; |
| |
| private static String[] initializePath(String propName) { |
| String ldPath = System.getProperty(propName, ""); |
| int ldLen = ldPath.length(); |
| char ps = File.pathSeparatorChar; |
| int psCount = 0; |
| |
| if (ClassLoaderHelper.allowsQuotedPathElements && |
| ldPath.indexOf('\"') >= 0) { |
| // First, remove quotes put around quoted parts of paths. |
| // Second, use a quotation mark as a new path separator. |
| // This will preserve any quoted old path separators. |
| char[] buf = new char[ldLen]; |
| int bufLen = 0; |
| for (int i = 0; i < ldLen; ++i) { |
| char ch = ldPath.charAt(i); |
| if (ch == '\"') { |
| while (++i < ldLen && |
| (ch = ldPath.charAt(i)) != '\"') { |
| buf[bufLen++] = ch; |
| } |
| } else { |
| if (ch == ps) { |
| psCount++; |
| ch = '\"'; |
| } |
| buf[bufLen++] = ch; |
| } |
| } |
| ldPath = new String(buf, 0, bufLen); |
| ldLen = bufLen; |
| ps = '\"'; |
| } else { |
| for (int i = ldPath.indexOf(ps); i >= 0; |
| i = ldPath.indexOf(ps, i + 1)) { |
| psCount++; |
| } |
| } |
| |
| String[] paths = new String[psCount + 1]; |
| int pathStart = 0; |
| for (int j = 0; j < psCount; ++j) { |
| int pathEnd = ldPath.indexOf(ps, pathStart); |
| paths[j] = (pathStart < pathEnd) ? |
| ldPath.substring(pathStart, pathEnd) : "."; |
| pathStart = pathEnd + 1; |
| } |
| paths[psCount] = (pathStart < ldLen) ? |
| ldPath.substring(pathStart, ldLen) : "."; |
| return paths; |
| } |
| |
| // Invoked in the java.lang.Runtime class to implement load and loadLibrary. |
| static void loadLibrary(Class<?> fromClass, String name, |
| boolean isAbsolute) { |
| ClassLoader loader = |
| (fromClass == null) ? null : fromClass.getClassLoader(); |
| if (sys_paths == null) { |
| usr_paths = initializePath("java.library.path"); |
| sys_paths = initializePath("sun.boot.library.path"); |
| } |
| if (isAbsolute) { |
| if (loadLibrary0(fromClass, new File(name))) { |
| return; |
| } |
| throw new UnsatisfiedLinkError("Can't load library: " + name); |
| } |
| if (loader != null) { |
| String libfilename = loader.findLibrary(name); |
| if (libfilename != null) { |
| File libfile = new File(libfilename); |
| if (!libfile.isAbsolute()) { |
| throw new UnsatisfiedLinkError( |
| "ClassLoader.findLibrary failed to return an absolute path: " + libfilename); |
| } |
| if (loadLibrary0(fromClass, libfile)) { |
| return; |
| } |
| throw new UnsatisfiedLinkError("Can't load " + libfilename); |
| } |
| } |
| for (String sys_path : sys_paths) { |
| File libfile = new File(sys_path, System.mapLibraryName(name)); |
| if (loadLibrary0(fromClass, libfile)) { |
| return; |
| } |
| libfile = ClassLoaderHelper.mapAlternativeName(libfile); |
| if (libfile != null && loadLibrary0(fromClass, libfile)) { |
| return; |
| } |
| } |
| if (loader != null) { |
| for (String usr_path : usr_paths) { |
| File libfile = new File(usr_path, System.mapLibraryName(name)); |
| if (loadLibrary0(fromClass, libfile)) { |
| return; |
| } |
| libfile = ClassLoaderHelper.mapAlternativeName(libfile); |
| if (libfile != null && loadLibrary0(fromClass, libfile)) { |
| return; |
| } |
| } |
| } |
| // Oops, it failed |
| throw new UnsatisfiedLinkError("no " + name + " in java.library.path"); |
| } |
| |
| static native String findBuiltinLib(String name); |
| |
| private static boolean loadLibrary0(Class<?> fromClass, final File file) { |
| // Check to see if we're attempting to access a static library |
| String name = findBuiltinLib(file.getName()); |
| boolean isBuiltin = (name != null); |
| if (!isBuiltin) { |
| name = AccessController.doPrivileged( |
| new PrivilegedAction<>() { |
| public String run() { |
| try { |
| return file.exists() ? file.getCanonicalPath() : null; |
| } catch (IOException e) { |
| return null; |
| } |
| } |
| }); |
| if (name == null) { |
| return false; |
| } |
| } |
| ClassLoader loader = |
| (fromClass == null) ? null : fromClass.getClassLoader(); |
| Vector<NativeLibrary> libs = |
| loader != null ? loader.nativeLibraries : systemNativeLibraries; |
| synchronized (libs) { |
| int size = libs.size(); |
| for (int i = 0; i < size; i++) { |
| NativeLibrary lib = libs.elementAt(i); |
| if (name.equals(lib.name)) { |
| return true; |
| } |
| } |
| |
| synchronized (loadedLibraryNames) { |
| if (loadedLibraryNames.contains(name)) { |
| throw new UnsatisfiedLinkError |
| ("Native Library " + |
| name + |
| " already loaded in another classloader"); |
| } |
| /* If the library is being loaded (must be by the same thread, |
| * because Runtime.load and Runtime.loadLibrary are |
| * synchronous). The reason is can occur is that the JNI_OnLoad |
| * function can cause another loadLibrary invocation. |
| * |
| * Thus we can use a static stack to hold the list of libraries |
| * we are loading. |
| * |
| * If there is a pending load operation for the library, we |
| * immediately return success; otherwise, we raise |
| * UnsatisfiedLinkError. |
| */ |
| int n = nativeLibraryContext.size(); |
| for (int i = 0; i < n; i++) { |
| NativeLibrary lib = nativeLibraryContext.elementAt(i); |
| if (name.equals(lib.name)) { |
| if (loader == lib.fromClass.getClassLoader()) { |
| return true; |
| } else { |
| throw new UnsatisfiedLinkError |
| ("Native Library " + |
| name + |
| " is being loaded in another classloader"); |
| } |
| } |
| } |
| NativeLibrary lib = new NativeLibrary(fromClass, name, isBuiltin); |
| nativeLibraryContext.push(lib); |
| try { |
| lib.load(name, isBuiltin); |
| } finally { |
| nativeLibraryContext.pop(); |
| } |
| if (lib.loaded) { |
| loadedLibraryNames.addElement(name); |
| libs.addElement(lib); |
| return true; |
| } |
| return false; |
| } |
| } |
| } |
| |
| // Invoked in the VM class linking code. |
| static long findNative(ClassLoader loader, String name) { |
| Vector<NativeLibrary> libs = |
| loader != null ? loader.nativeLibraries : systemNativeLibraries; |
| synchronized (libs) { |
| int size = libs.size(); |
| for (int i = 0; i < size; i++) { |
| NativeLibrary lib = libs.elementAt(i); |
| long entry = lib.find(name); |
| if (entry != 0) |
| return entry; |
| } |
| } |
| return 0; |
| } |
| |
| |
| // -- Assertion management -- |
| |
| final Object assertionLock; |
| |
| // The default toggle for assertion checking. |
| // @GuardedBy("assertionLock") |
| private boolean defaultAssertionStatus = false; |
| |
| // Maps String packageName to Boolean package default assertion status Note |
| // that the default package is placed under a null map key. If this field |
| // is null then we are delegating assertion status queries to the VM, i.e., |
| // none of this ClassLoader's assertion status modification methods have |
| // been invoked. |
| // @GuardedBy("assertionLock") |
| private Map<String, Boolean> packageAssertionStatus = null; |
| |
| // Maps String fullyQualifiedClassName to Boolean assertionStatus If this |
| // field is null then we are delegating assertion status queries to the VM, |
| // i.e., none of this ClassLoader's assertion status modification methods |
| // have been invoked. |
| // @GuardedBy("assertionLock") |
| Map<String, Boolean> classAssertionStatus = null; |
| |
| /** |
| * Sets the default assertion status for this class loader. This setting |
| * determines whether classes loaded by this class loader and initialized |
| * in the future will have assertions enabled or disabled by default. |
| * This setting may be overridden on a per-package or per-class basis by |
| * invoking {@link #setPackageAssertionStatus(String, boolean)} or {@link |
| * #setClassAssertionStatus(String, boolean)}. |
| * |
| * @param enabled |
| * {@code true} if classes loaded by this class loader will |
| * henceforth have assertions enabled by default, {@code false} |
| * if they will have assertions disabled by default. |
| * |
| * @since 1.4 |
| */ |
| public void setDefaultAssertionStatus(boolean enabled) { |
| synchronized (assertionLock) { |
| if (classAssertionStatus == null) |
| initializeJavaAssertionMaps(); |
| |
| defaultAssertionStatus = enabled; |
| } |
| } |
| |
| /** |
| * Sets the package default assertion status for the named package. The |
| * package default assertion status determines the assertion status for |
| * classes initialized in the future that belong to the named package or |
| * any of its "subpackages". |
| * |
| * <p> A subpackage of a package named p is any package whose name begins |
| * with "{@code p.}". For example, {@code javax.swing.text} is a |
| * subpackage of {@code javax.swing}, and both {@code java.util} and |
| * {@code java.lang.reflect} are subpackages of {@code java}. |
| * |
| * <p> In the event that multiple package defaults apply to a given class, |
| * the package default pertaining to the most specific package takes |
| * precedence over the others. For example, if {@code javax.lang} and |
| * {@code javax.lang.reflect} both have package defaults associated with |
| * them, the latter package default applies to classes in |
| * {@code javax.lang.reflect}. |
| * |
| * <p> Package defaults take precedence over the class loader's default |
| * assertion status, and may be overridden on a per-class basis by invoking |
| * {@link #setClassAssertionStatus(String, boolean)}. </p> |
| * |
| * @param packageName |
| * The name of the package whose package default assertion status |
| * is to be set. A {@code null} value indicates the unnamed |
| * package that is "current" |
| * (see section 7.4.2 of |
| * <cite>The Java™ Language Specification</cite>.) |
| * |
| * @param enabled |
| * {@code true} if classes loaded by this classloader and |
| * belonging to the named package or any of its subpackages will |
| * have assertions enabled by default, {@code false} if they will |
| * have assertions disabled by default. |
| * |
| * @since 1.4 |
| */ |
| public void setPackageAssertionStatus(String packageName, |
| boolean enabled) { |
| synchronized (assertionLock) { |
| if (packageAssertionStatus == null) |
| initializeJavaAssertionMaps(); |
| |
| packageAssertionStatus.put(packageName, enabled); |
| } |
| } |
| |
| /** |
| * Sets the desired assertion status for the named top-level class in this |
| * class loader and any nested classes contained therein. This setting |
| * takes precedence over the class loader's default assertion status, and |
| * over any applicable per-package default. This method has no effect if |
| * the named class has already been initialized. (Once a class is |
| * initialized, its assertion status cannot change.) |
| * |
| * <p> If the named class is not a top-level class, this invocation will |
| * have no effect on the actual assertion status of any class. </p> |
| * |
| * @param className |
| * The fully qualified class name of the top-level class whose |
| * assertion status is to be set. |
| * |
| * @param enabled |
| * {@code true} if the named class is to have assertions |
| * enabled when (and if) it is initialized, {@code false} if the |
| * class is to have assertions disabled. |
| * |
| * @since 1.4 |
| */ |
| public void setClassAssertionStatus(String className, boolean enabled) { |
| synchronized (assertionLock) { |
| if (classAssertionStatus == null) |
| initializeJavaAssertionMaps(); |
| |
| classAssertionStatus.put(className, enabled); |
| } |
| } |
| |
| /** |
| * Sets the default assertion status for this class loader to |
| * {@code false} and discards any package defaults or class assertion |
| * status settings associated with the class loader. This method is |
| * provided so that class loaders can be made to ignore any command line or |
| * persistent assertion status settings and "start with a clean slate." |
| * |
| * @since 1.4 |
| */ |
| public void clearAssertionStatus() { |
| /* |
| * Whether or not "Java assertion maps" are initialized, set |
| * them to empty maps, effectively ignoring any present settings. |
| */ |
| synchronized (assertionLock) { |
| classAssertionStatus = new HashMap<>(); |
| packageAssertionStatus = new HashMap<>(); |
| defaultAssertionStatus = false; |
| } |
| } |
| |
| /** |
| * Returns the assertion status that would be assigned to the specified |
| * class if it were to be initialized at the time this method is invoked. |
| * If the named class has had its assertion status set, the most recent |
| * setting will be returned; otherwise, if any package default assertion |
| * status pertains to this class, the most recent setting for the most |
| * specific pertinent package default assertion status is returned; |
| * otherwise, this class loader's default assertion status is returned. |
| * </p> |
| * |
| * @param className |
| * The fully qualified class name of the class whose desired |
| * assertion status is being queried. |
| * |
| * @return The desired assertion status of the specified class. |
| * |
| * @see #setClassAssertionStatus(String, boolean) |
| * @see #setPackageAssertionStatus(String, boolean) |
| * @see #setDefaultAssertionStatus(boolean) |
| * |
| * @since 1.4 |
| */ |
| boolean desiredAssertionStatus(String className) { |
| synchronized (assertionLock) { |
| // assert classAssertionStatus != null; |
| // assert packageAssertionStatus != null; |
| |
| // Check for a class entry |
| Boolean result = classAssertionStatus.get(className); |
| if (result != null) |
| return result.booleanValue(); |
| |
| // Check for most specific package entry |
| int dotIndex = className.lastIndexOf('.'); |
| if (dotIndex < 0) { // default package |
| result = packageAssertionStatus.get(null); |
| if (result != null) |
| return result.booleanValue(); |
| } |
| while(dotIndex > 0) { |
| className = className.substring(0, dotIndex); |
| result = packageAssertionStatus.get(className); |
| if (result != null) |
| return result.booleanValue(); |
| dotIndex = className.lastIndexOf('.', dotIndex-1); |
| } |
| |
| // Return the classloader default |
| return defaultAssertionStatus; |
| } |
| } |
| |
| // Set up the assertions with information provided by the VM. |
| // Note: Should only be called inside a synchronized block |
| private void initializeJavaAssertionMaps() { |
| // assert Thread.holdsLock(assertionLock); |
| |
| classAssertionStatus = new HashMap<>(); |
| packageAssertionStatus = new HashMap<>(); |
| AssertionStatusDirectives directives = retrieveDirectives(); |
| |
| for(int i = 0; i < directives.classes.length; i++) |
| classAssertionStatus.put(directives.classes[i], |
| directives.classEnabled[i]); |
| |
| for(int i = 0; i < directives.packages.length; i++) |
| packageAssertionStatus.put(directives.packages[i], |
| directives.packageEnabled[i]); |
| |
| defaultAssertionStatus = directives.deflt; |
| } |
| |
| // Retrieves the assertion directives from the VM. |
| private static native AssertionStatusDirectives retrieveDirectives(); |
| |
| |
| // -- Misc -- |
| |
| /** |
| * Returns the ConcurrentHashMap used as a storage for ClassLoaderValue(s) |
| * associated with this ClassLoader, creating it if it doesn't already exist. |
| */ |
| ConcurrentHashMap<?, ?> createOrGetClassLoaderValueMap() { |
| ConcurrentHashMap<?, ?> map = classLoaderValueMap; |
| if (map == null) { |
| map = new ConcurrentHashMap<>(); |
| boolean set = trySetObjectField("classLoaderValueMap", map); |
| if (!set) { |
| // beaten by someone else |
| map = classLoaderValueMap; |
| } |
| } |
| return map; |
| } |
| |
| // the storage for ClassLoaderValue(s) associated with this ClassLoader |
| private volatile ConcurrentHashMap<?, ?> classLoaderValueMap; |
| |
| /** |
| * Attempts to atomically set a volatile field in this object. Returns |
| * {@code true} if not beaten by another thread. Avoids the use of |
| * AtomicReferenceFieldUpdater in this class. |
| */ |
| private boolean trySetObjectField(String name, Object obj) { |
| Unsafe unsafe = Unsafe.getUnsafe(); |
| Class<?> k = ClassLoader.class; |
| long offset; |
| offset = unsafe.objectFieldOffset(k, name); |
| return unsafe.compareAndSetObject(this, offset, null, obj); |
| } |
| } |
| |
| /* |
| * A utility class that will enumerate over an array of enumerations. |
| */ |
| final class CompoundEnumeration<E> implements Enumeration<E> { |
| private final Enumeration<E>[] enums; |
| private int index; |
| |
| public CompoundEnumeration(Enumeration<E>[] enums) { |
| this.enums = enums; |
| } |
| |
| private boolean next() { |
| while (index < enums.length) { |
| if (enums[index] != null && enums[index].hasMoreElements()) { |
| return true; |
| } |
| index++; |
| } |
| return false; |
| } |
| |
| public boolean hasMoreElements() { |
| return next(); |
| } |
| |
| public E nextElement() { |
| if (!next()) { |
| throw new NoSuchElementException(); |
| } |
| return enums[index].nextElement(); |
| } |
| } |