| /* |
| * Copyright (c) 2000, 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.io.IOException; |
| import java.net.ProtocolFamily; |
| import java.nio.channels.*; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import java.util.Iterator; |
| import java.util.ServiceLoader; |
| import java.util.ServiceConfigurationError; |
| import sun.security.action.GetPropertyAction; |
| |
| |
| /** |
| * Service-provider class for selectors and selectable channels. |
| * |
| * <p> A selector 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> The system-wide default provider is used by the static <tt>open</tt> |
| * methods of the {@link java.nio.channels.DatagramChannel#open |
| * DatagramChannel}, {@link java.nio.channels.Pipe#open Pipe}, {@link |
| * java.nio.channels.Selector#open Selector}, {@link |
| * java.nio.channels.ServerSocketChannel#open ServerSocketChannel}, and {@link |
| * java.nio.channels.SocketChannel#open SocketChannel} classes. It is also |
| * used by the {@link java.lang.System#inheritedChannel System.inheritedChannel()} |
| * method. A program may make use of a provider other than the default provider |
| * by instantiating that provider and then directly invoking the <tt>open</tt> |
| * methods defined in this class. |
| * |
| * <p> All of the methods in this class are safe for use by multiple concurrent |
| * threads. </p> |
| * |
| * |
| * @author Mark Reinhold |
| * @author JSR-51 Expert Group |
| * @since 1.4 |
| */ |
| |
| public abstract class SelectorProvider { |
| |
| private static final Object lock = new Object(); |
| private static SelectorProvider provider = null; |
| |
| /** |
| * Initializes a new instance of this class. |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link RuntimePermission}<tt>("selectorProvider")</tt> |
| */ |
| protected SelectorProvider() { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("selectorProvider")); |
| } |
| |
| private static boolean loadProviderFromProperty() { |
| String cn = System.getProperty("java.nio.channels.spi.SelectorProvider"); |
| if (cn == null) |
| return false; |
| try { |
| Class<?> c = Class.forName(cn, true, |
| ClassLoader.getSystemClassLoader()); |
| provider = (SelectorProvider)c.newInstance(); |
| return true; |
| } 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 boolean loadProviderAsService() { |
| |
| ServiceLoader<SelectorProvider> sl = |
| ServiceLoader.load(SelectorProvider.class, |
| ClassLoader.getSystemClassLoader()); |
| Iterator<SelectorProvider> i = sl.iterator(); |
| for (;;) { |
| try { |
| if (!i.hasNext()) |
| return false; |
| provider = i.next(); |
| return true; |
| } catch (ServiceConfigurationError sce) { |
| if (sce.getCause() instanceof SecurityException) { |
| // Ignore the security exception, try the next provider |
| continue; |
| } |
| throw sce; |
| } |
| } |
| } |
| |
| /** |
| * Returns the system-wide default selector 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 |
| * <tt>java.nio.channels.spi.SelectorProvider</tt> 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 |
| * <tt>java.nio.channels.spi.SelectorProvider</tt> in the resource |
| * directory <tt>META-INF/services</tt>, 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 selector provider |
| */ |
| public static SelectorProvider provider() { |
| synchronized (lock) { |
| if (provider != null) |
| return provider; |
| return AccessController.doPrivileged( |
| new PrivilegedAction<SelectorProvider>() { |
| public SelectorProvider run() { |
| if (loadProviderFromProperty()) |
| return provider; |
| if (loadProviderAsService()) |
| return provider; |
| provider = sun.nio.ch.DefaultSelectorProvider.create(); |
| return provider; |
| } |
| }); |
| } |
| } |
| |
| /** |
| * Opens a datagram channel. |
| * |
| * @return The new channel |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract DatagramChannel openDatagramChannel() |
| throws IOException; |
| |
| /** |
| * Opens a datagram channel. |
| * |
| * @param family |
| * The protocol family |
| * |
| * @return A new datagram channel |
| * |
| * @throws UnsupportedOperationException |
| * If the specified protocol family is not supported |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @since 1.7 |
| */ |
| public abstract DatagramChannel openDatagramChannel(ProtocolFamily family) |
| throws IOException; |
| |
| /** |
| * Opens a pipe. |
| * |
| * @return The new pipe |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract Pipe openPipe() |
| throws IOException; |
| |
| /** |
| * Opens a selector. |
| * |
| * @return The new selector |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract AbstractSelector openSelector() |
| throws IOException; |
| |
| /** |
| * Opens a server-socket channel. |
| * |
| * @return The new channel |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract ServerSocketChannel openServerSocketChannel() |
| throws IOException; |
| |
| /** |
| * Opens a socket channel. |
| * |
| * @return The new channel |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public abstract SocketChannel openSocketChannel() |
| throws IOException; |
| |
| /** |
| * Returns the channel inherited from the entity that created this |
| * Java virtual machine. |
| * |
| * <p> On many operating systems a process, such as a Java virtual |
| * machine, can be started in a manner that allows the process to |
| * inherit a channel from the entity that created the process. The |
| * manner in which this is done is system dependent, as are the |
| * possible entities to which the channel may be connected. For example, |
| * on UNIX systems, the Internet services daemon (<i>inetd</i>) is used to |
| * start programs to service requests when a request arrives on an |
| * associated network port. In this example, the process that is started, |
| * inherits a channel representing a network socket. |
| * |
| * <p> In cases where the inherited channel represents a network socket |
| * then the {@link java.nio.channels.Channel Channel} type returned |
| * by this method is determined as follows: |
| * |
| * <ul> |
| * |
| * <li><p> If the inherited channel represents a stream-oriented connected |
| * socket then a {@link java.nio.channels.SocketChannel SocketChannel} is |
| * returned. The socket channel is, at least initially, in blocking |
| * mode, bound to a socket address, and connected to a peer. |
| * </p></li> |
| * |
| * <li><p> If the inherited channel represents a stream-oriented listening |
| * socket then a {@link java.nio.channels.ServerSocketChannel |
| * ServerSocketChannel} is returned. The server-socket channel is, at |
| * least initially, in blocking mode, and bound to a socket address. |
| * </p></li> |
| * |
| * <li><p> If the inherited channel is a datagram-oriented socket |
| * then a {@link java.nio.channels.DatagramChannel DatagramChannel} is |
| * returned. The datagram channel is, at least initially, in blocking |
| * mode, and bound to a socket address. |
| * </p></li> |
| * |
| * </ul> |
| * |
| * <p> In addition to the network-oriented channels described, this method |
| * may return other kinds of channels in the future. |
| * |
| * <p> The first invocation of this method creates the channel that is |
| * returned. Subsequent invocations of this method return the same |
| * channel. </p> |
| * |
| * @return The inherited channel, if any, otherwise <tt>null</tt>. |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link RuntimePermission}<tt>("inheritedChannel")</tt> |
| * |
| * @since 1.5 |
| */ |
| public Channel inheritedChannel() throws IOException { |
| return null; |
| } |
| |
| } |
