import java.net.*;
import java.util.*;

/**
  *利用MulticastSocket实现多人聊天---linux端
  */
public class MainClass5 extends Thread 
{
    
    private int  port=8888;
    private InetAddress addr=null;
    private DatagramPacket inPacket=null;//接收数据包
    private DatagramPacket outPacket=null;//发送数据包
    private  MulticastSocket socket=null;
        private Scanner sc=null;
    private byte[] inBuffer=null;
    private byte[] outBuffer=null;

    /**
      *初始化实例 ,
      */
    public void  init()
    {
        try
        {
        addr=InetAddress.getByName("230.0.0.1");
        socket=new MulticastSocket(port);    
            socket.joinGroup(addr);
            socket.setNetworkInterface(NetworkInterface.getByName("wlan0"));//设置网络接口后同一台机器上多个客户端间不能通信，类似与一台机器不能登录多个帐号
            System.out.println(socket.getNetworkInterface());
            socket.setLoopbackMode(true);
        sc=new Scanner(System.in);
        inBuffer=new byte[1024];
        inPacket =new DatagramPacket(inBuffer,inBuffer.length);//接收数据包
        new Thread(this).start();//启动run()线程 如果是new MainClass5().start()则会抛出java.lang.NullPointerException

        String line;
        while(true)
        {
            line=sc.nextLine();
            outBuffer=line.getBytes();
            outPacket=new DatagramPacket(outBuffer,outBuffer.length,addr,port);
            socket.send(outPacket);
            if(line.equals("quit"))
                break;
        }
        socket.close();
        }
        catch(Exception e)
        {
            System.out.println(e);
        }
        
        
        
    }

    /**
      *实现socket 接收广播数据并且打印到屏幕
      */
    public void run()
    {
        
        try
        {
        while(true)
        {
    
                socket.receive(inPacket);
                System.out.println("Form "+inPacket.getAddress()+" "+new String(inPacket.getData(),0,inPacket.getLength(),"gb2312"));
        }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    /**
      *main entru
      */
    public static void main(String[] args)
    {
        new MainClass5().init();
    }
}

import java.net.*;
import java.util.*;

/**
  *利用MulticastSocket实现多人聊天--windows端
  */
public class MainClass5 extends Thread 
{
    
    private int  port=8888;
    private InetAddress addr=null;
    private DatagramPacket inPacket=null;//接收数据包
    private DatagramPacket outPacket=null;//发送数据包
    private  MulticastSocket socket=null;
        private Scanner sc=null;
    private byte[] inBuffer=null;
    private byte[] outBuffer=null;

    /**
      *初始化实例 
      */
    public void  init()
    {
        try
        {
        addr=InetAddress.getByName("230.0.0.1");
        socket=new MulticastSocket(port);    
            socket.joinGroup(addr);
            socket.setNetworkInterface(NetworkInterface.getByName("eth0"));
            System.out.println("正在使用的网络接口 "+socket.getNetworkInterface());
            socket.setLoopbackMode(true);
        sc=new Scanner(System.in);
        inBuffer=new byte[1024];
        inPacket =new DatagramPacket(inBuffer,inBuffer.length);//接收数据包
        new Thread(this).start();//启动run()线程 如果是new MainClass5().start()则会抛出java.lang.NullPointerException

        String line;
        while(true)
        {
            line=sc.nextLine();
            outBuffer=line.getBytes();
            outPacket=new DatagramPacket(outBuffer,outBuffer.length,addr,port);
            socket.send(outPacket);
            if(line.equals("quit"))
                break;
        }
        socket.close();
        }
        catch(Exception e)
        {
            System.out.println(e);
        }
        
        
        
    }

    /**
      *实现socket 接收广播数据并且打印到屏幕
      */
    public void run()
    {
        //inBuffer=new byte[1024];
        //inPacket =new DatagramPacket(inBuffer,inBuffer.length);//接收数据包
        try
        {
        while(true)
        {
    
                socket.receive(inPacket);
                //
                System.out.println("Form "+inPacket.getAddress()+" "+new String(inPacket.getData(),0,inPacket.getLength(),"UTF-8"));
        }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    /**
      *main entru
      */
    public static void main(String[] args)
    {
        new MainClass5().init();
    }
}