- Java code
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)
------解决方案--------------------
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。