Java tutorial
/* * Copyright (c) 1997, 2007, 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 javax.net; import java.io.IOException; import java.net.InetAddress; import java.net.ServerSocket; import java.net.SocketException; /** * This class creates server sockets. It may be subclassed by other * factories, which create particular types of server sockets. This * provides a general framework for the addition of public socket-level * functionality. It is the server side analogue of a socket factory, * and similarly provides a way to capture a variety of policies related * to the sockets being constructed. * * <P> Like socket factories, server Socket factory instances have * methods used to create sockets. There is also an environment * specific default server socket factory; frameworks will often use * their own customized factory. * * @since 1.4 * @see SocketFactory * * @author David Brownell */ public abstract class ServerSocketFactory { // // NOTE: JDK 1.1 bug in class GC, this can get collected // even though it's always accessible via getDefault(). // private static ServerSocketFactory theFactory; /** * Creates a server socket factory. */ protected ServerSocketFactory() { /* NOTHING */ } /** * Returns a copy of the environment's default socket factory. * * @return the <code>ServerSocketFactory</code> */ public static ServerSocketFactory getDefault() { synchronized (ServerSocketFactory.class) { if (theFactory == null) { // // Different implementations of this method could // work rather differently. For example, driving // this from a system property, or using a different // implementation than JavaSoft's. // theFactory = new DefaultServerSocketFactory(); } } return theFactory; } /** * Returns an unbound server socket. The socket is configured with * the socket options (such as accept timeout) given to this factory. * * @return the unbound socket * @throws IOException if the socket cannot be created * @see java.net.ServerSocket#bind(java.net.SocketAddress) * @see java.net.ServerSocket#bind(java.net.SocketAddress, int) * @see java.net.ServerSocket#ServerSocket() */ public ServerSocket createServerSocket() throws IOException { throw new SocketException("Unbound server sockets not implemented"); } /** * Returns a server socket bound to the specified port. * The socket is configured with the socket options * (such as accept timeout) given to this factory. * <P> * If there is a security manager, its <code>checkListen</code> * method is called with the <code>port</code> argument as its * argument to ensure the operation is allowed. This could result * in a SecurityException. * * @param port the port to listen to * @return the <code>ServerSocket</code> * @throws IOException for networking errors * @throws SecurityException if a security manager exists and its * <code>checkListen</code> method doesn't allow the operation. * @throws IllegalArgumentException if the port parameter is outside the * specified range of valid port values, which is between 0 and * 65535, inclusive. * @see SecurityManager#checkListen * @see java.net.ServerSocket#ServerSocket(int) */ public abstract ServerSocket createServerSocket(int port) throws IOException; /** * Returns a server socket bound to the specified port, and uses the * specified connection backlog. The socket is configured with * the socket options (such as accept timeout) given to this factory. * <P> * The <code>backlog</code> argument must be a positive * value greater than 0. If the value passed if equal or less * than 0, then the default value will be assumed. * <P> * If there is a security manager, its <code>checkListen</code> * method is called with the <code>port</code> argument as its * argument to ensure the operation is allowed. This could result * in a SecurityException. * * @param port the port to listen to * @param backlog how many connections are queued * @return the <code>ServerSocket</code> * @throws IOException for networking errors * @throws SecurityException if a security manager exists and its * <code>checkListen</code> method doesn't allow the operation. * @throws IllegalArgumentException if the port parameter is outside the * specified range of valid port values, which is between 0 and * 65535, inclusive. * @see SecurityManager#checkListen * @see java.net.ServerSocket#ServerSocket(int, int) */ public abstract ServerSocket createServerSocket(int port, int backlog) throws IOException; /** * Returns a server socket bound to the specified port, * with a specified listen backlog and local IP. * <P> * The <code>ifAddress</code> argument can be used on a multi-homed * host for a <code>ServerSocket</code> that will only accept connect * requests to one of its addresses. If <code>ifAddress</code> is null, * it will accept connections on all local addresses. The socket is * configured with the socket options (such as accept timeout) given * to this factory. * <P> * The <code>backlog</code> argument must be a positive * value greater than 0. If the value passed if equal or less * than 0, then the default value will be assumed. * <P> * If there is a security manager, its <code>checkListen</code> * method is called with the <code>port</code> argument as its * argument to ensure the operation is allowed. This could result * in a SecurityException. * * @param port the port to listen to * @param backlog how many connections are queued * @param ifAddress the network interface address to use * @return the <code>ServerSocket</code> * @throws IOException for networking errors * @throws SecurityException if a security manager exists and its * <code>checkListen</code> method doesn't allow the operation. * @throws IllegalArgumentException if the port parameter is outside the * specified range of valid port values, which is between 0 and * 65535, inclusive. * @see SecurityManager#checkListen * @see java.net.ServerSocket#ServerSocket(int, int, java.net.InetAddress) */ public abstract ServerSocket createServerSocket(int port, int backlog, InetAddress ifAddress) throws IOException; } // // The default factory has NO intelligence. In fact it's not clear // what sort of intelligence servers need; the onus is on clients, // who have to know how to tunnel etc. // class DefaultServerSocketFactory extends ServerSocketFactory { DefaultServerSocketFactory() { /* NOTHING */ } public ServerSocket createServerSocket() throws IOException { return new ServerSocket(); } public ServerSocket createServerSocket(int port) throws IOException { return new ServerSocket(port); } public ServerSocket createServerSocket(int port, int backlog) throws IOException { return new ServerSocket(port, backlog); } public ServerSocket createServerSocket(int port, int backlog, InetAddress ifAddress) throws IOException { return new ServerSocket(port, backlog, ifAddress); } }