udpserverthread.java

用java写的用于C/S服务的网络应用程序

package udptest;

import java.io.*;
import java.net.*;

/**
 * <p>Title: </p>
 * <p>Description: </p>
 * <p>Copyright: Copyright (c) 2003</p>
 * <p>Company: </p>
 * @author not attributable
 * @version 1.0
 */

public class UDPServerThread extends Thread {
  private DatagramSocket UDPServerSocket = null;
          public UDPServerThread(int port)
          {
                  try
                  {
                          UDPServerSocket=new DatagramSocket(port);
                          System.out.println("邮件服务监听在端口："+UDPServerSocket.getLocalPort()+"\n");
                  }
                  catch(Exception e)
                  {
                          System.err.println(e);
                  }
          }

          public void run()
          {
                  if(UDPServerSocket == null)
                          return;
                  while(true)
                  {
                          try{
                                  byte dataBuf[]=new byte[512];
                                  DatagramPacket ServerPacket;
                                  InetAddress RemoteHost;
                                  int RemotePort;
                                  String Datagram,s;
                                  ServerPacket=new DatagramPacket(dataBuf,512);
                                  UDPServerSocket.receive(ServerPacket);
                                  RemoteHost=ServerPacket.getAddress();
                                  RemotePort=ServerPacket.getPort();
                                  Datagram=new String(ServerPacket.getData());
                                  System.out.println("收到如下主机发来的邮件："
                                      +RemoteHost.getHostName()
                                          +":\n"+Datagram);
                                  Datagram = new String(RemoteHost.getHostName()+
                                          ":\n MailServer  "+InetAddress.getLocalHost().getHostName()
                                          +" has already get your mails.");
                                  for(int i=0;i<512;i++) dataBuf[i]=0;
                                  Datagram.getBytes(0,Datagram.length(),dataBuf,0);
                                  ServerPacket=new DatagramPacket(dataBuf,dataBuf.length,
                                          RemoteHost,RemotePort);
                                  UDPServerSocket.send(ServerPacket);
                          }
                          catch(Exception e)
                          {
                                  System.err.println(e);
                          }
                  }
          }

  protected void finalize()
          {
                  if(UDPServerSocket != null)
                  {
                          UDPServerSocket.close();
                          UDPServerSocket=null;
                          System.out.println("关闭服务器的数据报连接！");
                  }
          }

}