| /* |
| * Copyright (c) 2007, 2013, 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.nio.channels.spi; |
| |
| import java.nio.channels.*; |
| import java.io.IOException; |
| import java.util.Iterator; |
| import java.util.ServiceLoader; |
| import java.util.ServiceConfigurationError; |
| import java.util.concurrent.*; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| |
| /** |
| * Service-provider class for asynchronous channels. |
| * |
| * <p> An asynchronous channel provider is a concrete subclass of this class that |
| * has a zero-argument constructor and implements the abstract methods specified |
| * below. A given invocation of the Java virtual machine maintains a single |
| * system-wide default provider instance, which is returned by the {@link |
| * #provider() provider} method. The first invocation of that method will locate |
| * the default provider as specified below. |
| * |
| * <p> All of the methods in this class are safe for use by multiple concurrent |
| * threads. </p> |
| * |
| * @since 1.7 |
| */ |
| |
| public abstract class AsynchronousChannelProvider { |
| private static Void checkPermission() { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("asynchronousChannelProvider")); |
| return null; |
| } |
| private AsynchronousChannelProvider(Void ignore) { } |
| |
| /** |
| * Initializes a new instance of this class. |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link RuntimePermission}{@code ("asynchronousChannelProvider")} |
| */ |
| protected AsynchronousChannelProvider() { |
| this(checkPermission()); |
| } |
| |
| // lazy initialization of default provider |
| private static class ProviderHolder { |
| static final AsynchronousChannelProvider provider = load(); |
| |
| private static AsynchronousChannelProvider load() { |
| return AccessController |
| .doPrivileged(new PrivilegedAction<>() { |
| public AsynchronousChannelProvider run() { |
| AsynchronousChannelProvider p; |
| p = loadProviderFromProperty(); |
| if (p != null) |
| return p; |
| p = loadProviderAsService(); |
| if (p != null) |
| return p; |
| return sun.nio.ch.DefaultAsynchronousChannelProvider.create(); |
| }}); |
| } |
| |
| private static AsynchronousChannelProvider loadProviderFromProperty() { |
| String cn = System.getProperty("java.nio.channels.spi.AsynchronousChannelProvider"); |
| if (cn == null) |
| return null; |
| try { |
| @SuppressWarnings("deprecation") |
| Object tmp = Class.forName(cn, true, |
| ClassLoader.getSystemClassLoader()).newInstance(); |
| return (AsynchronousChannelProvider)tmp; |
| } catch (ClassNotFoundException x) { |
| throw new ServiceConfigurationError(null, x); |
| } catch (IllegalAccessException x) { |
| throw new ServiceConfigurationError(null, x); |
| } catch (InstantiationException x) { |
| throw new ServiceConfigurationError(null, x); |
| } catch (SecurityException x) { |
| throw new ServiceConfigurationError(null, x); |
| } |
| } |
| |
| private static AsynchronousChannelProvider loadProviderAsService() { |
| ServiceLoader<AsynchronousChannelProvider> sl = |
| ServiceLoader.load(AsynchronousChannelProvider.class, |
| ClassLoader.getSystemClassLoader()); |
| Iterator<AsynchronousChannelProvider> i = sl.iterator(); |
| for (;;) { |
| try { |
| return (i.hasNext()) ? i.next() : null; |
| } catch (ServiceConfigurationError sce) { |
| if (sce.getCause() instanceof SecurityException) { |
| // Ignore the security exception, try the next provider |
| continue; |
| } |
| throw sce; |
| } |
| } |
| } |
| } |
| |
| /** |
| * Returns the system-wide default asynchronous channel provider for this |
| * invocation of the Java virtual machine. |
| * |
| * <p> The first invocation of this method locates the default provider |
| * object as follows: </p> |
| * |
| * <ol> |
| * |
| * <li><p> If the system property |
| * {@code java.nio.channels.spi.AsynchronousChannelProvider} is defined |
| * then it is taken to be the fully-qualified name of a concrete provider class. |
| * The class is loaded and instantiated; if this process fails then an |
| * unspecified error is thrown. </p></li> |
| * |
| * <li><p> If a provider class has been installed in a jar file that is |
| * visible to the system class loader, and that jar file contains a |
| * provider-configuration file named |
| * {@code java.nio.channels.spi.AsynchronousChannelProvider} in the resource |
| * directory {@code META-INF/services}, then the first class name |
| * specified in that file is taken. The class is loaded and |
| * instantiated; if this process fails then an unspecified error is |
| * thrown. </p></li> |
| * |
| * <li><p> Finally, if no provider has been specified by any of the above |
| * means then the system-default provider class is instantiated and the |
| * result is returned. </p></li> |
| * |
| * </ol> |
| * |
| * <p> Subsequent invocations of this method return the provider that was |
| * returned by the first invocation. </p> |
| * |
| * @return The system-wide default AsynchronousChannel provider |
| */ |
| public static AsynchronousChannelProvider provider() { |
| return ProviderHolder.provider; |
| } |
| |
| /** |
| * Constructs a new asynchronous channel group with a fixed thread pool. |
| * |
| * @param nThreads |
| * The number of threads in the pool |
| * @param threadFactory |
| * The factory to use when creating new threads |
| * |
| * @return A new asynchronous channel group |
| * |
| * @throws IllegalArgumentException |
| * If {@code nThreads <= 0} |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @see AsynchronousChannelGroup#withFixedThreadPool |
| */ |
| public abstract AsynchronousChannelGroup |
| openAsynchronousChannelGroup(int nThreads, ThreadFactory threadFactory) throws IOException; |
| |
| /** |
| * Constructs a new asynchronous channel group with the given thread pool. |
| * |
| * @param executor |
| * The thread pool |
| * @param initialSize |
| * A value {@code >=0} or a negative value for implementation |
| * specific default |
| * |
| * @return A new asynchronous channel group |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @see AsynchronousChannelGroup#withCachedThreadPool |
| */ |
| public abstract AsynchronousChannelGroup |
| openAsynchronousChannelGroup(ExecutorService executor, int initialSize) throws IOException; |
| |
| /** |
| * Opens an asynchronous server-socket channel. |
| * |
| * @param group |
| * The group to which the channel is bound, or {@code null} to |
| * bind to the default group |
| * |
| * @return The new channel |
| * |
| * @throws IllegalChannelGroupException |
| * If the provider that created the group differs from this provider |
| * @throws ShutdownChannelGroupException |
| * The group is shutdown |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract AsynchronousServerSocketChannel openAsynchronousServerSocketChannel |
| (AsynchronousChannelGroup group) throws IOException; |
| |
| /** |
| * Opens an asynchronous socket channel. |
| * |
| * @param group |
| * The group to which the channel is bound, or {@code null} to |
| * bind to the default group |
| * |
| * @return The new channel |
| * |
| * @throws IllegalChannelGroupException |
| * If the provider that created the group differs from this provider |
| * @throws ShutdownChannelGroupException |
| * The group is shutdown |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract AsynchronousSocketChannel openAsynchronousSocketChannel |
| (AsynchronousChannelGroup group) throws IOException; |
| } |