java关闭socket接收线程的问题

Question

package com.njust.socket;
import java.net.DatagramPacket;
import java.net.DatagramSocket;public class ServerUDPReceiver {
// 侦听的UDP端口号
private int port = -1;    
public static DatagramSocket socket_for_receive_udp = null;
    private byte[] buffer = new byte[8192];
    private DatagramPacket incomming = null;
    private boolean isFlag = true;
    //private Thread serverThread = null;
    
public ServerUDPReceiver(int i_port) {
port = i_port;
} public void startUDPReceiver() {
try {
socket_for_receive_udp = new DatagramSocket(this.port);
Thread serverThread = new Thread(new Runnable() {
public void run() {
try {
while (isFlag) {
try {
// 构造一个接收数据包
incomming = new DatagramPacket(buffer,buffer.length);
// 接收数据报
System.out.println("before receive!");
socket_for_receive_udp.receive(incomming); int length, offset;
byte[] realData = null;
length = incomming.getLength();
offset = incomming.getOffset();
realData = new byte[length];
System.arraycopy(buffer, offset, realData,offset, length);
System.out.println("reveive data:" + new String(realData)); } catch (Exception ee) {
ee.printStackTrace();
System.out.println("In while!!!");
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
socket_for_receive_udp.close();
}
}
});
serverThread.start();
} catch (Exception e) {
e.printStackTrace();
if (e.toString().indexOf(
"java.net.BindException: Address already in use: JVM_Bind") != -1) {
System.out.println("Server 已经启动，不能重复启动！");
}
}
}

public void stopUDPReceiver(){
if(socket_for_receive_udp!=null){
//serverThread.stop();
this.isFlag = false;
System.out.println("before socket close!");
socket_for_receive_udp.close();
}
}
}问题是这样的：首先启动startUDPReceiver，然后关闭stopUDPReceiver，提示错误如下：
java.net.SocketException: socket closed
at java.net.PlainDatagramSocketImpl.receive0(Native Method)
at java.net.PlainDatagramSocketImpl.receive(Unknown Source)
at java.net.DatagramSocket.receive(Unknown Source)
at com.njust.socket.ServerUDPReceiver$1.run(ServerUDPReceiver.java:29)
at java.lang.Thread.run(Unknown Source)

Answer 1

估计是它的事,
public void stopUDPReceiver(){
        if(socket_for_receive_udp!=null){
            //serverThread.stop();
            this.isFlag = false;
            System.out.println("before socket close!");
            socket_for_receive_udp.close();
        }
    }这个地方调用close但是你线程里面还在执行 连接被提前关闭，应该把这个close写到 while (isFlag) {...}后面,stopUDPReceiver()里置下this.isFlag = false;就行了。