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import java.net.DatagramPacket;import java.net.InetAddress;import java.net.MulticastSocket;import java.util.Scanner;//这是一个用udp接收广播的程序public class UDPclien { int port=6666; boolean b=false; Thread thread=null; //以下是建立7788的，本来这里调用了循环，我放到run方法里面去了 private void Receiver(InetAddress group) throws Exception { byte data[]=new byte[1024]; DatagramPacket packet=new DatagramPacket(data, data.length,group,port); MulticastSocket socket=new MulticastSocket(port); socket.joinGroup(group); socket.receive(packet); String s=new String(packet.getData()); System.out.println(s); } //把runnable对象独立出来了，这里调用了循环 private Runnable getRun() { Runnable runnable=new Runnable() { public void run() { try { InetAddress group=InetAddress.getByName("224.255.10.0"); while(true) { Receiver(group); if(b==true) { break; } } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }; return runnable; } //这里建立收听广播的线程 private void action(int a) { if(a==1) { if(thread==null) { thread=new Thread(getRun());thread.start(); } else if(!(thread.isAlive())){ thread=new Thread(getRun());thread.start(); } else { b=false; thread.run();//尝试过在这里加上循环，也没用 } } else if(a==0) { b=true; } else {} } private void seta(int a) { action(a); } public static void main(String[] args) { UDPclien clien=new UDPclien(); Scanner in=new Scanner(System.in); Thread thread=new Thread(new Runnable() { public void run() { while(true) { int a=in.nextInt(); if(a==2) { break; } clien.seta(a); } } }); thread.start(); }}我另外写了一个代码不断的发送广播，没有问题。这个代码，输入1可以一直接收广播，输入0会结束，但是再次输入1就只会执行一次。感觉不应该啊，我嵌套的好几次while死循环都不能实现再次启动，求大神指点 |
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