J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1996-2004 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.rmi.server; |
| 27 | |
| 28 | import java.net.MalformedURLException; |
| 29 | import java.net.URL; |
| 30 | import java.security.AccessController; |
| 31 | import java.security.PrivilegedAction; |
| 32 | import java.util.Iterator; |
| 33 | import java.util.ServiceLoader; |
| 34 | |
| 35 | /** |
| 36 | * <code>RMIClassLoader</code> comprises static methods to support |
| 37 | * dynamic class loading with RMI. Included are methods for loading |
| 38 | * classes from a network location (one or more URLs) and obtaining |
| 39 | * the location from which an existing class should be loaded by |
| 40 | * remote parties. These methods are used by the RMI runtime when |
| 41 | * marshalling and unmarshalling classes contained in the arguments |
| 42 | * and return values of remote method calls, and they also may be |
| 43 | * invoked directly by applications in order to mimic RMI's dynamic |
| 44 | * class loading behavior. |
| 45 | * |
| 46 | * <p>The implementation of the following static methods |
| 47 | * |
| 48 | * <ul> |
| 49 | * |
| 50 | * <li>{@link #loadClass(URL,String)} |
| 51 | * <li>{@link #loadClass(String,String)} |
| 52 | * <li>{@link #loadClass(String,String,ClassLoader)} |
| 53 | * <li>{@link #loadProxyClass(String,String[],ClassLoader)} |
| 54 | * <li>{@link #getClassLoader(String)} |
| 55 | * <li>{@link #getClassAnnotation(Class)} |
| 56 | * |
| 57 | * </ul> |
| 58 | * |
| 59 | * is provided by an instance of {@link RMIClassLoaderSpi}, the |
| 60 | * service provider interface for those methods. When one of the |
| 61 | * methods is invoked, its behavior is to delegate to a corresponding |
| 62 | * method on the service provider instance. The details of how each |
| 63 | * method delegates to the provider instance is described in the |
| 64 | * documentation for each particular method. |
| 65 | * |
| 66 | * <p>The service provider instance is chosen as follows: |
| 67 | * |
| 68 | * <ul> |
| 69 | * |
| 70 | * <li>If the system property |
| 71 | * <code>java.rmi.server.RMIClassLoaderSpi</code> is defined, then if |
| 72 | * its value equals the string <code>"default"</code>, the provider |
| 73 | * instance will be the value returned by an invocation of the {@link |
| 74 | * #getDefaultProviderInstance()} method, and for any other value, if |
| 75 | * a class named with the value of the property can be loaded by the |
| 76 | * system class loader (see {@link ClassLoader#getSystemClassLoader}) |
| 77 | * and that class is assignable to {@link RMIClassLoaderSpi} and has a |
| 78 | * public no-argument constructor, then that constructor will be |
| 79 | * invoked to create the provider instance. If the property is |
| 80 | * defined but any other of those conditions are not true, then an |
| 81 | * unspecified <code>Error</code> will be thrown to code that attempts |
| 82 | * to use <code>RMIClassLoader</code>, indicating the failure to |
| 83 | * obtain a provider instance. |
| 84 | * |
| 85 | * <li>If a resource named |
| 86 | * <code>META-INF/services/java.rmi.server.RMIClassLoaderSpi</code> is |
| 87 | * visible to the system class loader, then the contents of that |
| 88 | * resource are interpreted as a provider-configuration file, and the |
| 89 | * first class name specified in that file is used as the provider |
| 90 | * class name. If a class with that name can be loaded by the system |
| 91 | * class loader and that class is assignable to {@link |
| 92 | * RMIClassLoaderSpi} and has a public no-argument constructor, then |
| 93 | * that constructor will be invoked to create the provider instance. |
| 94 | * If the resource is found but a provider cannot be instantiated as |
| 95 | * described, then an unspecified <code>Error</code> will be thrown to |
| 96 | * code that attempts to use <code>RMIClassLoader</code>, indicating |
| 97 | * the failure to obtain a provider instance. |
| 98 | * |
| 99 | * <li>Otherwise, the provider instance will be the value returned by |
| 100 | * an invocation of the {@link #getDefaultProviderInstance()} method. |
| 101 | * |
| 102 | * </ul> |
| 103 | * |
| 104 | * @author Ann Wollrath |
| 105 | * @author Peter Jones |
| 106 | * @author Laird Dornin |
| 107 | * @see RMIClassLoaderSpi |
| 108 | * @since JDK1.1 |
| 109 | */ |
| 110 | public class RMIClassLoader { |
| 111 | |
| 112 | /** "default" provider instance */ |
| 113 | private static final RMIClassLoaderSpi defaultProvider = |
| 114 | newDefaultProviderInstance(); |
| 115 | |
| 116 | /** provider instance */ |
| 117 | private static final RMIClassLoaderSpi provider = |
| 118 | AccessController.doPrivileged( |
| 119 | new PrivilegedAction<RMIClassLoaderSpi>() { |
| 120 | public RMIClassLoaderSpi run() { return initializeProvider(); } |
| 121 | }); |
| 122 | |
| 123 | /* |
| 124 | * Disallow anyone from creating one of these. |
| 125 | */ |
| 126 | private RMIClassLoader() {} |
| 127 | |
| 128 | /** |
| 129 | * Loads the class with the specified <code>name</code>. |
| 130 | * |
| 131 | * <p>This method delegates to {@link #loadClass(String,String)}, |
| 132 | * passing <code>null</code> as the first argument and |
| 133 | * <code>name</code> as the second argument. |
| 134 | * |
| 135 | * @param name the name of the class to load |
| 136 | * |
| 137 | * @return the <code>Class</code> object representing the loaded class |
| 138 | * |
| 139 | * @throws MalformedURLException if a provider-specific URL used |
| 140 | * to load classes is invalid |
| 141 | * |
| 142 | * @throws ClassNotFoundException if a definition for the class |
| 143 | * could not be found at the codebase location |
| 144 | * |
| 145 | * @deprecated replaced by <code>loadClass(String,String)</code> method |
| 146 | * @see #loadClass(String,String) |
| 147 | */ |
| 148 | @Deprecated |
| 149 | public static Class<?> loadClass(String name) |
| 150 | throws MalformedURLException, ClassNotFoundException |
| 151 | { |
| 152 | return loadClass((String) null, name); |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Loads a class from a codebase URL. |
| 157 | * |
| 158 | * If <code>codebase</code> is <code>null</code>, then this method |
| 159 | * will behave the same as {@link #loadClass(String,String)} with a |
| 160 | * <code>null</code> <code>codebase</code> and the given class name. |
| 161 | * |
| 162 | * <p>This method delegates to the |
| 163 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} |
| 164 | * method of the provider instance, passing the result of invoking |
| 165 | * {@link URL#toString} on the given URL (or <code>null</code> if |
| 166 | * <code>codebase</code> is null) as the first argument, |
| 167 | * <code>name</code> as the second argument, |
| 168 | * and <code>null</code> as the third argument. |
| 169 | * |
| 170 | * @param codebase the URL to load the class from, or <code>null</code> |
| 171 | * |
| 172 | * @param name the name of the class to load |
| 173 | * |
| 174 | * @return the <code>Class</code> object representing the loaded class |
| 175 | * |
| 176 | * @throws MalformedURLException if <code>codebase</code> is |
| 177 | * <code>null</code> and a provider-specific URL used |
| 178 | * to load classes is invalid |
| 179 | * |
| 180 | * @throws ClassNotFoundException if a definition for the class |
| 181 | * could not be found at the specified URL |
| 182 | */ |
| 183 | public static Class<?> loadClass(URL codebase, String name) |
| 184 | throws MalformedURLException, ClassNotFoundException |
| 185 | { |
| 186 | return provider.loadClass( |
| 187 | codebase != null ? codebase.toString() : null, name, null); |
| 188 | } |
| 189 | |
| 190 | /** |
| 191 | * Loads a class from a codebase URL path. |
| 192 | * |
| 193 | * <p>This method delegates to the |
| 194 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} |
| 195 | * method of the provider instance, passing <code>codebase</code> |
| 196 | * as the first argument, <code>name</code> as the second argument, |
| 197 | * and <code>null</code> as the third argument. |
| 198 | * |
| 199 | * @param codebase the list of URLs (separated by spaces) to load |
| 200 | * the class from, or <code>null</code> |
| 201 | * |
| 202 | * @param name the name of the class to load |
| 203 | * |
| 204 | * @return the <code>Class</code> object representing the loaded class |
| 205 | * |
| 206 | * @throws MalformedURLException if <code>codebase</code> is |
| 207 | * non-<code>null</code> and contains an invalid URL, or if |
| 208 | * <code>codebase</code> is <code>null</code> and a provider-specific |
| 209 | * URL used to load classes is invalid |
| 210 | * |
| 211 | * @throws ClassNotFoundException if a definition for the class |
| 212 | * could not be found at the specified location |
| 213 | * |
| 214 | * @since 1.2 |
| 215 | */ |
| 216 | public static Class<?> loadClass(String codebase, String name) |
| 217 | throws MalformedURLException, ClassNotFoundException |
| 218 | { |
| 219 | return provider.loadClass(codebase, name, null); |
| 220 | } |
| 221 | |
| 222 | /** |
| 223 | * Loads a class from a codebase URL path, optionally using the |
| 224 | * supplied loader. |
| 225 | * |
| 226 | * This method should be used when the caller would like to make |
| 227 | * available to the provider implementation an additional contextual |
| 228 | * class loader to consider, such as the loader of a caller on the |
| 229 | * stack. Typically, a provider implementation will attempt to |
| 230 | * resolve the named class using the given <code>defaultLoader</code>, |
| 231 | * if specified, before attempting to resolve the class from the |
| 232 | * codebase URL path. |
| 233 | * |
| 234 | * <p>This method delegates to the |
| 235 | * {@link RMIClassLoaderSpi#loadClass(String,String,ClassLoader)} |
| 236 | * method of the provider instance, passing <code>codebase</code> |
| 237 | * as the first argument, <code>name</code> as the second argument, |
| 238 | * and <code>defaultLoader</code> as the third argument. |
| 239 | * |
| 240 | * @param codebase the list of URLs (separated by spaces) to load |
| 241 | * the class from, or <code>null</code> |
| 242 | * |
| 243 | * @param name the name of the class to load |
| 244 | * |
| 245 | * @param defaultLoader additional contextual class loader |
| 246 | * to use, or <code>null</code> |
| 247 | * |
| 248 | * @return the <code>Class</code> object representing the loaded class |
| 249 | * |
| 250 | * @throws MalformedURLException if <code>codebase</code> is |
| 251 | * non-<code>null</code> and contains an invalid URL, or if |
| 252 | * <code>codebase</code> is <code>null</code> and a provider-specific |
| 253 | * URL used to load classes is invalid |
| 254 | * |
| 255 | * @throws ClassNotFoundException if a definition for the class |
| 256 | * could not be found at the specified location |
| 257 | * |
| 258 | * @since 1.4 |
| 259 | */ |
| 260 | public static Class<?> loadClass(String codebase, String name, |
| 261 | ClassLoader defaultLoader) |
| 262 | throws MalformedURLException, ClassNotFoundException |
| 263 | { |
| 264 | return provider.loadClass(codebase, name, defaultLoader); |
| 265 | } |
| 266 | |
| 267 | /** |
| 268 | * Loads a dynamic proxy class (see {@link java.lang.reflect.Proxy}) |
| 269 | * that implements a set of interfaces with the given names |
| 270 | * from a codebase URL path. |
| 271 | * |
| 272 | * <p>The interfaces will be resolved similar to classes loaded via |
| 273 | * the {@link #loadClass(String,String)} method using the given |
| 274 | * <code>codebase</code>. |
| 275 | * |
| 276 | * <p>This method delegates to the |
| 277 | * {@link RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader)} |
| 278 | * method of the provider instance, passing <code>codebase</code> |
| 279 | * as the first argument, <code>interfaces</code> as the second argument, |
| 280 | * and <code>defaultLoader</code> as the third argument. |
| 281 | * |
| 282 | * @param codebase the list of URLs (space-separated) to load |
| 283 | * classes from, or <code>null</code> |
| 284 | * |
| 285 | * @param interfaces the names of the interfaces for the proxy class |
| 286 | * to implement |
| 287 | * |
| 288 | * @param defaultLoader additional contextual class loader |
| 289 | * to use, or <code>null</code> |
| 290 | * |
| 291 | * @return a dynamic proxy class that implements the named interfaces |
| 292 | * |
| 293 | * @throws MalformedURLException if <code>codebase</code> is |
| 294 | * non-<code>null</code> and contains an invalid URL, or |
| 295 | * if <code>codebase</code> is <code>null</code> and a provider-specific |
| 296 | * URL used to load classes is invalid |
| 297 | * |
| 298 | * @throws ClassNotFoundException if a definition for one of |
| 299 | * the named interfaces could not be found at the specified location, |
| 300 | * or if creation of the dynamic proxy class failed (such as if |
| 301 | * {@link java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[])} |
| 302 | * would throw an <code>IllegalArgumentException</code> for the given |
| 303 | * interface list) |
| 304 | * |
| 305 | * @since 1.4 |
| 306 | */ |
| 307 | public static Class<?> loadProxyClass(String codebase, String[] interfaces, |
| 308 | ClassLoader defaultLoader) |
| 309 | throws ClassNotFoundException, MalformedURLException |
| 310 | { |
| 311 | return provider.loadProxyClass(codebase, interfaces, defaultLoader); |
| 312 | } |
| 313 | |
| 314 | /** |
| 315 | * Returns a class loader that loads classes from the given codebase |
| 316 | * URL path. |
| 317 | * |
| 318 | * <p>The class loader returned is the class loader that the |
| 319 | * {@link #loadClass(String,String)} method would use to load classes |
| 320 | * for the same <code>codebase</code> argument. |
| 321 | * |
| 322 | * <p>This method delegates to the |
| 323 | * {@link RMIClassLoaderSpi#getClassLoader(String)} method |
| 324 | * of the provider instance, passing <code>codebase</code> as the argument. |
| 325 | * |
| 326 | * <p>If there is a security manger, its <code>checkPermission</code> |
| 327 | * method will be invoked with a |
| 328 | * <code>RuntimePermission("getClassLoader")</code> permission; |
| 329 | * this could result in a <code>SecurityException</code>. |
| 330 | * The provider implementation of this method may also perform further |
| 331 | * security checks to verify that the calling context has permission to |
| 332 | * connect to all of the URLs in the codebase URL path. |
| 333 | * |
| 334 | * @param codebase the list of URLs (space-separated) from which |
| 335 | * the returned class loader will load classes from, or <code>null</code> |
| 336 | * |
| 337 | * @return a class loader that loads classes from the given codebase URL |
| 338 | * path |
| 339 | * |
| 340 | * @throws MalformedURLException if <code>codebase</code> is |
| 341 | * non-<code>null</code> and contains an invalid URL, or |
| 342 | * if <code>codebase</code> is <code>null</code> and a provider-specific |
| 343 | * URL used to identify the class loader is invalid |
| 344 | * |
| 345 | * @throws SecurityException if there is a security manager and the |
| 346 | * invocation of its <code>checkPermission</code> method fails, or |
| 347 | * if the caller does not have permission to connect to all of the |
| 348 | * URLs in the codebase URL path |
| 349 | * |
| 350 | * @since 1.3 |
| 351 | */ |
| 352 | public static ClassLoader getClassLoader(String codebase) |
| 353 | throws MalformedURLException, SecurityException |
| 354 | { |
| 355 | return provider.getClassLoader(codebase); |
| 356 | } |
| 357 | |
| 358 | /** |
| 359 | * Returns the annotation string (representing a location for |
| 360 | * the class definition) that RMI will use to annotate the class |
| 361 | * descriptor when marshalling objects of the given class. |
| 362 | * |
| 363 | * <p>This method delegates to the |
| 364 | * {@link RMIClassLoaderSpi#getClassAnnotation(Class)} method |
| 365 | * of the provider instance, passing <code>cl</code> as the argument. |
| 366 | * |
| 367 | * @param cl the class to obtain the annotation for |
| 368 | * |
| 369 | * @return a string to be used to annotate the given class when |
| 370 | * it gets marshalled, or <code>null</code> |
| 371 | * |
| 372 | * @throws NullPointerException if <code>cl</code> is <code>null</code> |
| 373 | * |
| 374 | * @since 1.2 |
| 375 | */ |
| 376 | /* |
| 377 | * REMIND: Should we say that the returned class annotation will or |
| 378 | * should be a (space-separated) list of URLs? |
| 379 | */ |
| 380 | public static String getClassAnnotation(Class<?> cl) { |
| 381 | return provider.getClassAnnotation(cl); |
| 382 | } |
| 383 | |
| 384 | /** |
| 385 | * Returns the canonical instance of the default provider |
| 386 | * for the service provider interface {@link RMIClassLoaderSpi}. |
| 387 | * If the system property <code>java.rmi.server.RMIClassLoaderSpi</code> |
| 388 | * is not defined, then the <code>RMIClassLoader</code> static |
| 389 | * methods |
| 390 | * |
| 391 | * <ul> |
| 392 | * |
| 393 | * <li>{@link #loadClass(URL,String)} |
| 394 | * <li>{@link #loadClass(String,String)} |
| 395 | * <li>{@link #loadClass(String,String,ClassLoader)} |
| 396 | * <li>{@link #loadProxyClass(String,String[],ClassLoader)} |
| 397 | * <li>{@link #getClassLoader(String)} |
| 398 | * <li>{@link #getClassAnnotation(Class)} |
| 399 | * |
| 400 | * </ul> |
| 401 | * |
| 402 | * will use the canonical instance of the default provider |
| 403 | * as the service provider instance. |
| 404 | * |
| 405 | * <p>If there is a security manager, its |
| 406 | * <code>checkPermission</code> method will be invoked with a |
| 407 | * <code>RuntimePermission("setFactory")</code> permission; this |
| 408 | * could result in a <code>SecurityException</code>. |
| 409 | * |
| 410 | * <p>The default service provider instance implements |
| 411 | * {@link RMIClassLoaderSpi} as follows: |
| 412 | * |
| 413 | * <blockquote> |
| 414 | * |
| 415 | * <p>The <b>{@link RMIClassLoaderSpi#getClassAnnotation(Class) |
| 416 | * getClassAnnotation}</b> method returns a <code>String</code> |
| 417 | * representing the codebase URL path that a remote party should |
| 418 | * use to download the definition for the specified class. The |
| 419 | * format of the returned string is a path of URLs separated by |
| 420 | * spaces. |
| 421 | * |
| 422 | * The codebase string returned depends on the defining class |
| 423 | * loader of the specified class: |
| 424 | * |
| 425 | * <ul> |
| 426 | * |
| 427 | * <p><li>If the class loader is the system class loader (see |
| 428 | * {@link ClassLoader#getSystemClassLoader}), a parent of the |
| 429 | * system class loader such as the loader used for installed |
| 430 | * extensions, or the bootstrap class loader (which may be |
| 431 | * represented by <code>null</code>), then the value of the |
| 432 | * <code>java.rmi.server.codebase</code> property (or possibly an |
| 433 | * earlier cached value) is returned, or |
| 434 | * <code>null</code> is returned if that property is not set. |
| 435 | * |
| 436 | * <p><li>Otherwise, if the class loader is an instance of |
| 437 | * <code>URLClassLoader</code>, then the returned string is a |
| 438 | * space-separated list of the external forms of the URLs returned |
| 439 | * by invoking the <code>getURLs</code> methods of the loader. If |
| 440 | * the <code>URLClassLoader</code> was created by this provider to |
| 441 | * service an invocation of its <code>loadClass</code> or |
| 442 | * <code>loadProxyClass</code> methods, then no permissions are |
| 443 | * required to get the associated codebase string. If it is an |
| 444 | * arbitrary other <code>URLClassLoader</code> instance, then if |
| 445 | * there is a security manager, its <code>checkPermission</code> |
| 446 | * method will be invoked once for each URL returned by the |
| 447 | * <code>getURLs</code> method, with the permission returned by |
| 448 | * invoking <code>openConnection().getPermission()</code> on each |
| 449 | * URL; if any of those invocations throws a |
| 450 | * <code>SecurityException</code> or an <code>IOException</code>, |
| 451 | * then the value of the <code>java.rmi.server.codebase</code> |
| 452 | * property (or possibly an earlier cached value) is returned, or |
| 453 | * <code>null</code> is returned if that property is not set. |
| 454 | * |
| 455 | * <p><li>Finally, if the class loader is not an instance of |
| 456 | * <code>URLClassLoader</code>, then the value of the |
| 457 | * <code>java.rmi.server.codebase</code> property (or possibly an |
| 458 | * earlier cached value) is returned, or |
| 459 | * <code>null</code> is returned if that property is not set. |
| 460 | * |
| 461 | * </ul> |
| 462 | * |
| 463 | * <p>For the implementations of the methods described below, |
| 464 | * which all take a <code>String</code> parameter named |
| 465 | * <code>codebase</code> that is a space-separated list of URLs, |
| 466 | * each invocation has an associated <i>codebase loader</i> that |
| 467 | * is identified using the <code>codebase</code> argument in |
| 468 | * conjunction with the current thread's context class loader (see |
| 469 | * {@link Thread#getContextClassLoader()}). When there is a |
| 470 | * security manager, this provider maintains an internal table of |
| 471 | * class loader instances (which are at least instances of {@link |
| 472 | * java.net.URLClassLoader}) keyed by the pair of their parent |
| 473 | * class loader and their codebase URL path (an ordered list of |
| 474 | * URLs). If the <code>codebase</code> argument is <code>null</code>, |
| 475 | * the codebase URL path is the value of the system property |
| 476 | * <code>java.rmi.server.codebase</code> or possibly an |
| 477 | * earlier cached value. For a given codebase URL path passed as the |
| 478 | * <code>codebase</code> argument to an invocation of one of the |
| 479 | * below methods in a given context, the codebase loader is the |
| 480 | * loader in the table with the specified codebase URL path and |
| 481 | * the current thread's context class loader as its parent. If no |
| 482 | * such loader exists, then one is created and added to the table. |
| 483 | * The table does not maintain strong references to its contained |
| 484 | * loaders, in order to allow them and their defined classes to be |
| 485 | * garbage collected when not otherwise reachable. In order to |
| 486 | * prevent arbitrary untrusted code from being implicitly loaded |
| 487 | * into a virtual machine with no security manager, if there is no |
| 488 | * security manager set, the codebase loader is just the current |
| 489 | * thread's context class loader (the supplied codebase URL path |
| 490 | * is ignored, so remote class loading is disabled). |
| 491 | * |
| 492 | * <p>The <b>{@link RMIClassLoaderSpi#getClassLoader(String) |
| 493 | * getClassLoader}</b> method returns the codebase loader for the |
| 494 | * specified codebase URL path. If there is a security manager, |
| 495 | * then if the calling context does not have permission to connect |
| 496 | * to all of the URLs in the codebase URL path, a |
| 497 | * <code>SecurityException</code> will be thrown. |
| 498 | * |
| 499 | * <p>The <b>{@link |
| 500 | * RMIClassLoaderSpi#loadClass(String,String,ClassLoader) |
| 501 | * loadClass}</b> method attempts to load the class with the |
| 502 | * specified name as follows: |
| 503 | * |
| 504 | * <blockquote> |
| 505 | * |
| 506 | * If the <code>defaultLoader</code> argument is |
| 507 | * non-<code>null</code>, it first attempts to load the class with the |
| 508 | * specified <code>name</code> using the |
| 509 | * <code>defaultLoader</code>, such as by evaluating |
| 510 | * |
| 511 | * <pre> |
| 512 | * Class.forName(name, false, defaultLoader) |
| 513 | * </pre> |
| 514 | * |
| 515 | * If the class is successfully loaded from the |
| 516 | * <code>defaultLoader</code>, that class is returned. If an |
| 517 | * exception other than <code>ClassNotFoundException</code> is |
| 518 | * thrown, that exception is thrown to the caller. |
| 519 | * |
| 520 | * <p>Next, the <code>loadClass</code> method attempts to load the |
| 521 | * class with the specified <code>name</code> using the codebase |
| 522 | * loader for the specified codebase URL path. |
| 523 | * If there is a security manager, then the calling context |
| 524 | * must have permission to connect to all of the URLs in the |
| 525 | * codebase URL path; otherwise, the current thread's context |
| 526 | * class loader will be used instead of the codebase loader. |
| 527 | * |
| 528 | * </blockquote> |
| 529 | * |
| 530 | * <p>The <b>{@link |
| 531 | * RMIClassLoaderSpi#loadProxyClass(String,String[],ClassLoader) |
| 532 | * loadProxyClass}</b> method attempts to return a dynamic proxy |
| 533 | * class with the named interface as follows: |
| 534 | * |
| 535 | * <blockquote> |
| 536 | * |
| 537 | * <p>If the <code>defaultLoader</code> argument is |
| 538 | * non-<code>null</code> and all of the named interfaces can be |
| 539 | * resolved through that loader, then, |
| 540 | * |
| 541 | * <ul> |
| 542 | * |
| 543 | * <li>if all of the resolved interfaces are <code>public</code>, |
| 544 | * then it first attempts to obtain a dynamic proxy class (using |
| 545 | * {@link |
| 546 | * java.lang.reflect.Proxy#getProxyClass(ClassLoader,Class[]) |
| 547 | * Proxy.getProxyClass}) for the resolved interfaces defined in |
| 548 | * the codebase loader; if that attempt throws an |
| 549 | * <code>IllegalArgumentException</code>, it then attempts to |
| 550 | * obtain a dynamic proxy class for the resolved interfaces |
| 551 | * defined in the <code>defaultLoader</code>. If both attempts |
| 552 | * throw <code>IllegalArgumentException</code>, then this method |
| 553 | * throws a <code>ClassNotFoundException</code>. If any other |
| 554 | * exception is thrown, that exception is thrown to the caller. |
| 555 | * |
| 556 | * <li>if all of the non-<code>public</code> resolved interfaces |
| 557 | * are defined in the same class loader, then it attempts to |
| 558 | * obtain a dynamic proxy class for the resolved interfaces |
| 559 | * defined in that loader. |
| 560 | * |
| 561 | * <li>otherwise, a <code>LinkageError</code> is thrown (because a |
| 562 | * class that implements all of the specified interfaces cannot be |
| 563 | * defined in any loader). |
| 564 | * |
| 565 | * </ul> |
| 566 | * |
| 567 | * <p>Otherwise, if all of the named interfaces can be resolved |
| 568 | * through the codebase loader, then, |
| 569 | * |
| 570 | * <ul> |
| 571 | * |
| 572 | * <li>if all of the resolved interfaces are <code>public</code>, |
| 573 | * then it attempts to obtain a dynamic proxy class for the |
| 574 | * resolved interfaces in the codebase loader. If the attempt |
| 575 | * throws an <code>IllegalArgumentException</code>, then this |
| 576 | * method throws a <code>ClassNotFoundException</code>. |
| 577 | * |
| 578 | * <li>if all of the non-<code>public</code> resolved interfaces |
| 579 | * are defined in the same class loader, then it attempts to |
| 580 | * obtain a dynamic proxy class for the resolved interfaces |
| 581 | * defined in that loader. |
| 582 | * |
| 583 | * <li>otherwise, a <code>LinkageError</code> is thrown (because a |
| 584 | * class that implements all of the specified interfaces cannot be |
| 585 | * defined in any loader). |
| 586 | * |
| 587 | * </ul> |
| 588 | * |
| 589 | * <p>Otherwise, a <code>ClassNotFoundException</code> is thrown |
| 590 | * for one of the named interfaces that could not be resolved. |
| 591 | * |
| 592 | * </blockquote> |
| 593 | * |
| 594 | * </blockquote> |
| 595 | * |
| 596 | * @return the canonical instance of the default service provider |
| 597 | * |
| 598 | * @throws SecurityException if there is a security manager and the |
| 599 | * invocation of its <code>checkPermission</code> method fails |
| 600 | * |
| 601 | * @since 1.4 |
| 602 | */ |
| 603 | public static RMIClassLoaderSpi getDefaultProviderInstance() { |
| 604 | SecurityManager sm = System.getSecurityManager(); |
| 605 | if (sm != null) { |
| 606 | sm.checkPermission(new RuntimePermission("setFactory")); |
| 607 | } |
| 608 | return defaultProvider; |
| 609 | } |
| 610 | |
| 611 | /** |
| 612 | * Returns the security context of the given class loader. |
| 613 | * |
| 614 | * @param loader a class loader from which to get the security context |
| 615 | * |
| 616 | * @return the security context |
| 617 | * |
| 618 | * @deprecated no replacement. As of the Java 2 platform v1.2, RMI no |
| 619 | * longer uses this method to obtain a class loader's security context. |
| 620 | * @see java.lang.SecurityManager#getSecurityContext() |
| 621 | */ |
| 622 | @Deprecated |
| 623 | public static Object getSecurityContext(ClassLoader loader) |
| 624 | { |
| 625 | return sun.rmi.server.LoaderHandler.getSecurityContext(loader); |
| 626 | } |
| 627 | |
| 628 | /** |
| 629 | * Creates an instance of the default provider class. |
| 630 | */ |
| 631 | private static RMIClassLoaderSpi newDefaultProviderInstance() { |
| 632 | return new RMIClassLoaderSpi() { |
| 633 | public Class<?> loadClass(String codebase, String name, |
| 634 | ClassLoader defaultLoader) |
| 635 | throws MalformedURLException, ClassNotFoundException |
| 636 | { |
| 637 | return sun.rmi.server.LoaderHandler.loadClass( |
| 638 | codebase, name, defaultLoader); |
| 639 | } |
| 640 | |
| 641 | public Class<?> loadProxyClass(String codebase, |
| 642 | String[] interfaces, |
| 643 | ClassLoader defaultLoader) |
| 644 | throws MalformedURLException, ClassNotFoundException |
| 645 | { |
| 646 | return sun.rmi.server.LoaderHandler.loadProxyClass( |
| 647 | codebase, interfaces, defaultLoader); |
| 648 | } |
| 649 | |
| 650 | public ClassLoader getClassLoader(String codebase) |
| 651 | throws MalformedURLException |
| 652 | { |
| 653 | return sun.rmi.server.LoaderHandler.getClassLoader(codebase); |
| 654 | } |
| 655 | |
| 656 | public String getClassAnnotation(Class<?> cl) { |
| 657 | return sun.rmi.server.LoaderHandler.getClassAnnotation(cl); |
| 658 | } |
| 659 | }; |
| 660 | } |
| 661 | |
| 662 | /** |
| 663 | * Chooses provider instance, following above documentation. |
| 664 | * |
| 665 | * This method assumes that it has been invoked in a privileged block. |
| 666 | */ |
| 667 | private static RMIClassLoaderSpi initializeProvider() { |
| 668 | /* |
| 669 | * First check for the system property being set: |
| 670 | */ |
| 671 | String providerClassName = |
| 672 | System.getProperty("java.rmi.server.RMIClassLoaderSpi"); |
| 673 | |
| 674 | if (providerClassName != null) { |
| 675 | if (providerClassName.equals("default")) { |
| 676 | return defaultProvider; |
| 677 | } |
| 678 | |
| 679 | try { |
| 680 | Class<? extends RMIClassLoaderSpi> providerClass = |
| 681 | Class.forName(providerClassName, false, |
| 682 | ClassLoader.getSystemClassLoader()) |
| 683 | .asSubclass(RMIClassLoaderSpi.class); |
| 684 | return providerClass.newInstance(); |
| 685 | |
| 686 | } catch (ClassNotFoundException e) { |
| 687 | throw new NoClassDefFoundError(e.getMessage()); |
| 688 | } catch (IllegalAccessException e) { |
| 689 | throw new IllegalAccessError(e.getMessage()); |
| 690 | } catch (InstantiationException e) { |
| 691 | throw new InstantiationError(e.getMessage()); |
| 692 | } catch (ClassCastException e) { |
| 693 | Error error = new LinkageError( |
| 694 | "provider class not assignable to RMIClassLoaderSpi"); |
| 695 | error.initCause(e); |
| 696 | throw error; |
| 697 | } |
| 698 | } |
| 699 | |
| 700 | /* |
| 701 | * Next look for a provider configuration file installed: |
| 702 | */ |
| 703 | Iterator<RMIClassLoaderSpi> iter = |
| 704 | ServiceLoader.load(RMIClassLoaderSpi.class, |
| 705 | ClassLoader.getSystemClassLoader()).iterator(); |
| 706 | if (iter.hasNext()) { |
| 707 | try { |
| 708 | return iter.next(); |
| 709 | } catch (ClassCastException e) { |
| 710 | Error error = new LinkageError( |
| 711 | "provider class not assignable to RMIClassLoaderSpi"); |
| 712 | error.initCause(e); |
| 713 | throw error; |
| 714 | } |
| 715 | } |
| 716 | |
| 717 | /* |
| 718 | * Finally, return the canonical instance of the default provider. |
| 719 | */ |
| 720 | return defaultProvider; |
| 721 | } |
| 722 | } |