multicastsockettest.java

疯狂Java讲义_源码(含Java设计模式CHM

import java.awt.*;
import java.net.*;
import java.io.*;
import java.util.*;
/**
 * Description:
 * <br/>Copyright (C), 2008-2010, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee [e-mail]
 * @version  1.0
 */
//让该类实现Runnable接口，该类的实例可作为线程的target
public class MulticastSocketTest implements Runnable
{
	//使用常量作为本程序的多点广播IP地址
	private static final String BROADCAST_IP
		= "230.0.0.1";
	//使用常量作为本程序的多点广播目的的端口
	public static final int BROADCAST_PORT = 30000;
	//定义每个数据报的最大大小为4K
	private static final int DATA_LEN = 4096;

	
	//定义本程序的MulticastSocket实例
	private MulticastSocket socket = null;
	private InetAddress broadcastAddress = null;
	private Scanner scan = null;
	//定义接收网络数据的字节数组
	byte[] inBuff = new byte[DATA_LEN];
	//以指定字节数组创建准备接受数据的DatagramPacket对象
	private DatagramPacket inPacket = 
		new DatagramPacket(inBuff , inBuff.length);
	//定义一个用于发送的DatagramPacket对象
	private DatagramPacket outPacket = null;
	public void init()throws IOException
	{
		try
		{
			//创建用于发送、接收数据的MulticastSocket对象
			//因为该MulticastSocket对象需要接收，所以有指定端口
			socket = new MulticastSocket(BROADCAST_PORT);
			broadcastAddress = InetAddress.getByName(BROADCAST_IP);
			//将该socket加入指定的多点广播地址
			socket.joinGroup(broadcastAddress);
			//设置本MulticastSocket发送的数据报被回送到自身
			socket.setLoopbackMode(false);
			//初始化发送用的DatagramSocket，它包含一个长度为0的字节数组
			outPacket = new DatagramPacket(new byte[0] , 0 ,
				broadcastAddress , BROADCAST_PORT);
			//启动以本实例的run()方法作为线程体的线程
			new Thread(this).start();
			//创建键盘输入流
			scan = new Scanner(System.in);
			//不断读取键盘输入
			while(scan.hasNextLine())
			{
				//将键盘输入的一行字符串转换字节数组
				byte[] buff = scan.nextLine().getBytes();
				//设置发送用的DatagramPacket里的字节数据
				outPacket.setData(buff);
				//发送数据报
				socket.send(outPacket);
			}
		}
		finally
		{
			socket.close();
		}
	}
	
	public void run()
	{
		try
		{
			while(true)
			{
				//读取Socket中的数据，读到的数据放在inPacket所封装的字节数组里。
				socket.receive(inPacket);
				//打印输出从socket中读取的内容
				System.out.println("聊天信息：" + new String(inBuff , 0 , 
					inPacket.getLength()));
			}
		}
		//捕捉异常
		catch (IOException ex)
		{
			ex.printStackTrace();
			try
			{
				if (socket != null)
				{
					//让该Socket离开该多点IP广播地址
					socket.leaveGroup(broadcastAddress);
					//关闭该Socket对象
					socket.close();
				}
				System.exit(1);	
			}
			catch (IOException e)
			{
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args) 
		throws IOException
	{
		new MulticastSocketTest().init();
	}
}