udpserver.java

这是利用java编的计算机网络的关于客户与服务端的通信小程序

//UDPServer.java

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

class UDPServer
{
 public static void main(String args[])throws Exception
 {
  DatagramSocket serverSocket=new DatagramSocket(9876);//在端口9876构造DatagramSocket serverSocket,所有发送和接收的数据都将通过该套接字,因为UDP是无连接的
  System.out.println("基于UDP通信方式已经建立:"); 
  byte[]receiveData=new byte[32];
  byte[]sendData=new byte[32];
  boolean flag=true;
  while(flag)
  {
  DatagramPacket receivePacket=new DatagramPacket(receiveData,receiveData.length);
  serverSocket.receive(receivePacket);
  String sentence=new String(receivePacket.getData());//从分组中提取数据,并放入String sentence中
  System.out.println("From Client:\t\t"+sentence);
  InetAddress IPAddress=receivePacket.getAddress();//提取了IP地址
  int port=receivePacket.getPort();//提取了由客户机选择的客户机端口,对服务器来说获得端口号和IP地址是必要的,只有这样才能和客户机对话
  BufferedReader inFromUser=new BufferedReader(new InputStreamReader(System.in));
  String information=inFromUser.readLine();
  if(information.equals("byebye")) flag=false;
  sendData=information.getBytes();
  DatagramPacket sendPacket=new DatagramPacket(sendData,sendData.length,IPAddress,port);
  serverSocket.send(sendPacket);
 
  }
 }
}