2. 接收端：

public class Reci implements Runnable {

private DatagramSocket ds;

public Reci(DatagramSocket ds)
{
this.ds= ds;
}

@Override
public void run() {
// TODO Auto-generated method stub
try {
while(true){

byte[] buf=new byte[1024];
DatagramPacket dp = new DatagramPacket(buf, buf.length);

ds.receive(dp);

String ipString=dp.getAddress().getHostAddress();
int port =dp.getPort();
String data= new String(dp.getData(),0,dp.getLength());

System.out.println("ip :"+ipString+"port :"+port+"data　:"+data);

if(data.equals("886"))
{
System.out.println(ipString+"...退出聊天室");
}
}
} catch (IOException e) {

}
}

}

3. 单线程进程启动

public class ChatMultiThreadDemo {

public static void main(String[] args) throws SocketException {

DatagramSocket send = new DatagramSocket();
DatagramSocket reci = new DatagramSocket(10001);

new Thread(new Send(send)).start();
new Thread(new Reci(reci)).start();


}
}