使用udp广播实现简单局域网群聊

package com.iaiai.test;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * 
 * <br/>
 * Title: Main.java<br/>
 *
 * Http: iaiai.iteye.com<br/>
 * Create time: 2013-1-29 上午11:41:09<br/>
 * <br/>
 * 
 * @author 丸子
 * @version 0.0.1
 */
public class Main {

  private DatagramSocket ds;
  private int port;

  public Main(int port) throws IOException {
    this.port = port;
    ds = new DatagramSocket(port);
    // ds.setBroadcast(true);
  }

  public static void main(String[] args) throws Exception {
    int port = 9876;
    Main main = new Main(port);
    main.start();
  }

  void start() throws Exception {
    startServer();
    Scanner scanner = new Scanner(System.in);
    String name = "";
    while (name.isEmpty()) {
      System.out.print("请输入名称:");
      name = scanner.nextLine();
    }
    String msg = "";
    while (!"exit".equalsIgnoreCase(msg)) {
      if (!msg.isEmpty()) {
        send(name, msg);
      }
      System.out.print("输入消息:>");
      msg = scanner.nextLine();
    }
    System.exit(0);
  }

  private void send(String name, String msg) throws IOException {
    String sendMsg = encoder(name) + "," + encoder(msg);
    try {
      byte[] buf = sendMsg.getBytes("UTF-8");
      DatagramPacket dp = new DatagramPacket(buf, buf.length);
      dp.setSocketAddress(new InetSocketAddress("255.255.255.255", port));
      ds.send(dp);
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
  }

  private static String encoder(String str) {
    try {
      return URLEncoder.encode(str, "UTF-8");
    } catch (UnsupportedEncodingException e) {
      return "";
    }
  }

  private void startServer() throws SocketException {
    ExecutorService threadPool = Executors.newCachedThreadPool();
    threadPool.submit(new UdpReceive(ds));
  }

  static class UdpReceive implements Runnable {
    private DatagramSocket ds;

    UdpReceive(DatagramSocket ds) {
      this.ds = ds;
    }

    @Override
    public void run() {
      byte[] buf = new byte[1024];
      DatagramPacket dp = new DatagramPacket(buf, buf.length);
      while (true) {
        try {
          ds.receive(dp);
          String str = new String(dp.getData(), dp.getOffset(), dp.getLength());
          String[] msgs = str.split(",");
          String name = decode(msgs[0]);
          String msg = decode(msgs[1]);
          System.out.println(name + " 说:" + msg + "   (" + dp.getSocketAddress() + ")");
          // System.out.println("收到来自:"+dp.getSocketAddress()+"的消息   "+new
          // String(dp.getData(),dp.getOffset(),dp.getLength()));
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }

    private static String decode(String str) {
      try {
        return URLDecoder.decode(str, "UTF-8");
      } catch (UnsupportedEncodingException e) {
        return "";
      }
    }
  }

}