[置顶] Java UDP套接字编程

客户机UDPClient.java：

import java.io.*; 
import java.net.*; 
  
class UDPSocket { 
    public static void main(String args[]) throws Exception 
    { 
  
      BufferedReader inFromUser = 
         new BufferedReader(new InputStreamReader(System.in)); 
  
      DatagramSocket ClientSocket = new DatagramSocket(); 
  
      InetAddress IPAddress = InetAddress.getByName("hostname"); 
  
      byte[ ] sendData = new byte[1024]; 
      byte[ ] receiveData = new byte[1024]; 
  
      String sentence = inFromUser.readLine(); 
      sendData = sentence.getBytes();      
      DatagramPacket sendPacket = 
         new DatagramPacket(sendData, sendData.length, IPAddress, 9876); 
  
      ClientSocket.send(sendPacket); 
  
      DatagramPacket receivePacket = 
         new DatagramPacket(receiveData, receiveData.length); 
  
      ClientSocket.receive(receivePacket); 
  
      String modifiedSentence = 
         new String(receivePacket.getData()); 
  
      System.out.println("FROM Server:" + modifiedSentence); 
     ServerSocket.close(); 
      } 
}

服务器UDPServer.java：

import java.io.*; 
import java.net.*; 
  
class UDPServer { 
  public static void main(String args[]) throws Exception 
    { 
  
      DatagramSocket ServerSocket = new DatagramSocket(9876); 
  
      byte[] receiveData = new byte[1024]; 
      byte[] sendData  = new byte[1024]; 
  
      while(true) 
        { 
  
          DatagramPacket receivePacket = 
             new DatagramPacket(receiveData, receiveData.length); 
 ServerSocket.receive(receivePacket); 

          String sentence = new String(receivePacket.getData()); 
  
          InetAddress IPAddress = receivePacket.getAddress(); 
  
          int port = receivePacket.getPort(); 
  
          String capitalizedSentence = sentence.toUpperCase(); 

          sendData = capitalizedSentence.getBytes(); 
  
          DatagramPacket sendPacket = 
             new DatagramPacket(sendData, sendData.length, IPAddress, 
                               port); 
  
          ServerSocket.send(sendPacket); 
        } 
    } 
}