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/>
 * E-Mail: [e-mail]<br/>
 * QQ: 176291935<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 "";
			}
		}
	}

}