mixedcastserver.java

JAVA网络编程技术内幕一书的源代码

/*
 * 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.*;

public class MixedcastServer {
  public static void main (String[] args) throws IOException {
    if ((args.length != 2) || (args[1].indexOf (":") < 0))
      throw new IllegalArgumentException
        ("Syntax: MixedcastServer <server port> <group>:<port>");
 
    int serverPort = Integer.parseInt (args[0]);
    int idx = args[1].indexOf (":");
    InetAddress group = InetAddress.getByName (args[1].substring (0, idx));
    int port = Integer.parseInt (args[1].substring (idx + 1));
  
    init (serverPort, group, port);
    while (true) {
      relay ();
    }
  }

  protected static DatagramSocket inSocket;
  protected static MulticastSocket outSocket;
  protected static DatagramPacket incoming, outgoing;

  protected static void init (int serverPort, InetAddress group, int port) throws IOException {
    inSocket = new DatagramSocket (serverPort);
    outSocket = new MulticastSocket ();
    outSocket.setTimeToLive (1);
    byte[] buffer = new byte[65508];
    incoming = new DatagramPacket (buffer, buffer.length);
    outgoing = new DatagramPacket (buffer, buffer.length, group, port);
  }

  protected static void relay () throws IOException {
    incoming.setLength (incoming.getData ().length);
    inSocket.receive (incoming);
    outgoing.setLength (incoming.getLength ());
    outSocket.send (outgoing);
  }
}