[转]java 组播

1. 组播知识介绍： http://blog.csdn.net/happy_david/article/details/1569209

2. java 组播实现：来自： http://blog.csdn.net/a352193394/article/details/7395600

下面来演示一下使用Java Socket的组播类实现一个组播的小案例

首先是接收端

package com.bird.test;

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.util.Date;

/**
 * 组播的客户端
 * @author Bird
 *
 */
public class MulticastReceive {


    public static void main(String[] args) throws Exception {
        test();
    }

    public static void test() throws Exception{
        InetAddress group = InetAddress.getByName("224.0.0.2");//组播地址
        int port = 8888;
        MulticastSocket msr = null;//创建组播套接字
        try {
            msr = new MulticastSocket(port);
            msr.joinGroup(group);//加入连接
            byte[] buffer = new byte[8192];
            System.out.println("接收数据包启动！(启动时间: "+new Date()+")");
            while(true){
                //建立一个指定缓冲区大小的数据包
                DatagramPacket dp = new DatagramPacket(buffer, buffer.length);
                msr.receive(dp);
                String s = new String(dp.getData(),0,dp.getLength());
                //解码组播数据包
                System.out.println(s);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(msr!=null){
                try {
                    msr.leaveGroup(group);
                    msr.close();
                } catch (Exception e2) {
                    // TODO: handle exception
                }
            }
        }
    }


}

然后是发送端

package com.bird.test;

import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.util.Date;

/**
 * 组播的服务端
 * @author Bird
 *
 */
public class MulticastSender {

    public static void server() throws Exception{
        InetAddress group = InetAddress.getByName("224.0.0.2");//组播地址
        int port = 8888;
        MulticastSocket mss = null;
        try {
            mss = new MulticastSocket(port);
            mss.joinGroup(group);
            System.out.println("发送数据包启动！（启动时间"+new Date()+")");

            while(true){
                String message = "Hello "+new Date();
                byte[] buffer = message.getBytes();
                DatagramPacket dp = new DatagramPacket(buffer, buffer.length,group,port);
                mss.send(dp);
                System.out.println("发送数据包给 "+group+":"+port);
                Thread.sleep(1000);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            try {
                if(mss!=null){
                    mss.leaveGroup(group);
                    mss.close();
                }
            } catch (Exception e2) {
                // TODO: handle exception
            }
        }
    }

    public static void main(String[] args) throws Exception {
        server();
    }
}

通过开启多个接收端，然后开启发送端，就可以实现组播的效果