talkserverthread.java

java tutorial.sun公司官方出品。java入门书籍。最新版

/*
 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

/*
 * Java(TM) SE 6 version.
 * Code is the same as 1.0 code.
 */

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

class TalkServerThread extends Thread {
    public Socket socket;
    public DataInputStream is;
    public DataOutputStream os;
    TalkServer server;
    boolean DEBUG = false;

    public String toString() {
        return "TalkServerThread: socket = " + socket
               + "; is = " + is
               + "; os = " + os;
    }

    TalkServerThread(Socket socket, TalkServer server) throws IOException {
        super("TalkServer");

        is = new DataInputStream(socket.getInputStream());
        os = new DataOutputStream(socket.getOutputStream());

        if (is == null) {
            System.err.println("TalkServerThread: Input stream seemed "
                               + "to be created successfully, but it's null.");
            throw new IOException();
        }

        if (os == null) {
            System.err.println("TalkServerThread: Output stream seemed "
                               + "to be created successfully, but it's null.");
            throw new IOException();
        }

        this.socket = socket;
        this.server = server;
    }

    public void run() {
        while (socket != null) {
            try {
                //Read data.
                String str = is.readUTF();

                //Pass it on.
                if (str != null) {
                    server.forwardString(str, this);
                }
            } catch (EOFException e) { //No more data on this socket...
                server.forwardString("SERVER SAYS other applet disconnected",
                                     this);
                cleanup();
                return;
            } catch (NullPointerException e) { //Socket doesn't exist...
                server.forwardString("SERVER SAYS no socket to other applet",
                                     this);
                cleanup();
                return;
            } catch (IOException e) { //Read problem..
                server.forwardString("SERVER SAYS socket trouble with other applet",
                                     this);
                cleanup();
                return;
            } catch (Exception e) { //Unknown exception. Complain and quit.
                System.err.println("Exception on is.readUTF():");
                e.printStackTrace();
                cleanup();
                return;
            }
        }
    }

    protected void finalize() {
        cleanup();
    }

    void cleanup() {
        try {
            if (is != null) {
                is.close();
                is = null;
            }
        } catch (Exception e) {} //Ignore errors.

        try {
            if (os != null) {
                os.close();
                os = null;
            }
        } catch (Exception e) {} //Ignore errors.

        try {
            if (socket != null) {
                socket.close();
                socket = null;
            }
        } catch (Exception e) {} //Ignore errors.
    }

}