www.pudn.com > jnp-src.rar > MulticastChat.java

/*
 * Java Network Programming, Second Edition
 * Merlin Hughes, Michael Shoffner, Derek Hamner
 * Manning Publications Company; ISBN 188477749X
 *
 * http://nitric.com/jnp/
 *
 * Copyright (c) 1997-1999 Merlin Hughes, Michael Shoffner, Derek Hamner;
 * all rights reserved; see license.txt for details.
 */

import java.io.*; 
import java.net.*; 
import java.awt.*; 
import java.awt.event.*; 
 
public class MulticastChat implements Runnable, WindowListener, ActionListener { 
  protected InetAddress group; 
  protected int port; 
   
  public MulticastChat (InetAddress group, int port) { 
    this.group = group; 
    this.port = port; 
    initAWT (); 
  } 
 
  protected Frame frame; 
  protected TextArea output; 
  protected TextField input; 
   
  protected void initAWT () { 
    frame = new Frame 
      ("MulticastChat [" + group.getHostAddress () + ":" + port + "]"); 
    frame.addWindowListener (this); 
    output = new TextArea (); 
    output.setEditable (false); 
    input = new TextField (); 
    input.addActionListener (this); 
    frame.setLayout (new BorderLayout ()); 
    frame.add (output, "Center"); 
    frame.add (input, "South"); 
    frame.pack (); 
  } 
 
  protected Thread listener; 
   
  public synchronized void start () throws IOException { 
    if (listener == null) { 
      initNet (); 
      listener = new Thread (this); 
      listener.start (); 
      frame.setVisible (true); 
    } 
  } 
 
  protected MulticastSocket socket; 
  protected DatagramPacket outgoing, incoming; 
   
  protected void initNet () throws IOException { 
    socket = new MulticastSocket (port); 
    socket.setTimeToLive (1); 
    socket.joinGroup (group); 
    outgoing = new DatagramPacket (new byte[1], 1, group, port); 
    incoming = new DatagramPacket (new byte[65508], 65508); 
  } 
 
  public synchronized void stop () throws IOException { 
    frame.setVisible (false); 
    if (listener != null) { 
      listener.interrupt (); 
      listener = null; 
      try { 
        socket.leaveGroup (group); 
      } finally { 
        socket.close (); 
      } 
    } 
  } 
 
  public void windowOpened (WindowEvent event) { 
    input.requestFocus (); 
  } 
 
  public void windowClosing (WindowEvent event) { 
    try { 
      stop (); 
    } catch (IOException ex) { 
      ex.printStackTrace (); 
    } 
  } 
 
  public void windowClosed (WindowEvent event) {} 
  public void windowIconified (WindowEvent event) {} 
  public void windowDeiconified (WindowEvent event) {} 
  public void windowActivated (WindowEvent event) {} 
  public void windowDeactivated (WindowEvent event) {} 
 
  public void actionPerformed (ActionEvent event) { 
    try { 
      byte[] utf = event.getActionCommand ().getBytes ("UTF8"); 
      outgoing.setData (utf); 
      outgoing.setLength (utf.length); 
      socket.send (outgoing); 
      input.setText (""); 
    } catch (IOException ex) { 
      handleIOException (ex); 
    } 
  } 
 
  protected synchronized void handleIOException (IOException ex) { 
    if (listener != null) { 
      output.append (ex + "\n"); 
      input.setVisible (false); 
      frame.validate (); 
      if (listener != Thread.currentThread ()) 
        listener.interrupt (); 
      listener = null; 
      try { 
        socket.leaveGroup (group); 
      } catch (IOException ignored) { 
      } 
      socket.close (); 
    } 
  } 
 
  public void run () { 
    try { 
      while (!Thread.interrupted ()) { 
        incoming.setLength (incoming.getData ().length); 
        socket.receive (incoming); 
        String message = new String 
          (incoming.getData (), 0, incoming.getLength (), "UTF8"); 
        output.append (message + "\n"); 
      } 
    } catch (IOException ex) { 
      handleIOException (ex); 
    } 
  } 
 
  public static void main (String[] args) throws IOException { 
    if ((args.length != 1) || (args[0].indexOf (":") < 0)) 
      throw new IllegalArgumentException 
        ("Syntax: MulticastChat :"); 
     
    int idx = args[0].indexOf (":"); 
      InetAddress group = InetAddress.getByName (args[0].substring (0, idx)); 
    int port = Integer.parseInt (args[0].substring (idx + 1)); 
     
    MulticastChat chat = new MulticastChat (group, port); 
    chat.start (); 
  } 
}