multihostsocketfactory.java

Java Threads, 2Ed (Source）

/*
 *
 * Copyright (c) 1997-1999 Scott Oaks and Henry Wong. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software
 * and its documentation for NON-COMMERCIAL purposes and
 * without fee is hereby granted.
 *
 * This sample source code is provided for example only,
 * on an unsupported, as-is basis. 
 *
 * AUTHOR MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE, OR NON-INFRINGEMENT. AUTHOR SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
 * CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE
 * PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT
 * NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE
 * SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE
 * SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE
 * PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES").  AUTHOR
 * SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR
 * HIGH RISK ACTIVITIES.
 */


import java.net.*;
import java.io.*;

public class MultiHostSocketFactory {
	private Socket sock;
	private Thread target;

	class ConnectThread extends Thread {
		String host;
		int port;
		MultiHostSocketFactory parent;

		ConnectThread(String host, int port, MultiHostSocketFactory 
parent) {
			this.host = host;
			this.port = port;
			this.parent = parent;
		}

		public void run() {
			try {
				Socket tempSock = new Socket(host, port);
				synchronized(parent) {
					if (parent.target != this)
						return;
					parent.sock = tempSock;
					parent.notify();
				}
			} catch (IOException ioe) {
				synchronized(parent) {
					parent.notify();
				}
			}
		}
	}

	public Socket makeSocket(String hosts[], int port) {
		int i;
		sock = null;
		synchronized(this) {
			for (i = 0; i < hosts.length && sock == null; i++) {
				ConnectThread th =
						new ConnectThread(hosts[i], 
port, this);
				target = th;
				th.start();
				try {
				    wait(30 * 1000);
				} catch (InterruptedException ie) {}
				if (sock == null)
					th.interrupt();
			}
		}
		return sock;
	}

	public static void main(String args[]) {
	    System.out.println("Got " +
		new MultiHostSocketFactory().makeSocket(args, 7));
	}
}