UDP传输----java网络编程(1)

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本文通过一个简单的客户端和服务端的Java代码示例介绍了UDP协议的基本使用方法。客户端向服务器发送消息，服务器接收并返回响应，展示了UDP的数据包构造和解析过程。

网络传输需要一个服务器接收数据，然后客户端向服务器发送数据，UDP传输，把数据封装成数据包后传输。

下来看一段代码

客户端代码

import java.net.*;

public class Client{

   public Client(){
        try{
           byte buf[] = new byte[200];
           DatagramPacket willRecv = new DatagramPacket(buf,200);
           DatagramSocket socket = new DatagramSocket();
           InetAddress ip = InetAddress.getByName("127.0.0.1");
           for(int i=0;i<10;i++){
              String str ="www.itflight.net"+i;
              DatagramPacket willsend = StringToPacket(str,ip,8000);
              //发送数据包
              socket.send(willsend);
              //接受数据包
              socket.receive(willRecv);
              String message = PacketToString(willRecv);
              System.out.println(message);
           }
       }catch(Exception e){
            e.printStackTrace();
       }
   }
   public static void main(String[] args){
      new Client();
   }
    //字符串转换为数据包，UDP传输使用
  DatagramPacket StringToPacket(String message,InetAddress ip,int port){
       int length = message.length();
       byte buf[] = new byte[length];
       buf = message.getBytes();
       DatagramPacket rdp = new DatagramPacket(buf,0,length,ip,port);
       return rdp;
  }
   String PacketToString(DatagramPacket dp){
        int length = dp.getLength();
        byte buf[] = new byte[length];
        buf = dp.getData();
        String str = new String(buf,0,length);
        return str;
   }
}

服务器端代码

import java.net.*;

public class Server{

   public Server(){
        try{
           byte buf[] = new byte[200];
           DatagramPacket willRecv = new DatagramPacket(buf,200);
           DatagramSocket socket = new DatagramSocket(8000);
          
           for(int i=0;i<10;i++){
             //服务端先接受数据包
              socket.receive(willRecv);
              String message = PacketToString(willRecv);
              System.out.println(message);
            
              InetAddress ip = willRecv.getAddress();
              int port = willRecv.getPort();
              String str ="航班:"+i;
              DatagramPacket willsend = StringToPacket(str,ip,port);
              //发送数据包
              socket.send(willsend);
              
           }
       }catch(Exception e){
            e.printStackTrace();
       }
   }
   public static void main(String[] args){
      new Server();
   }
    //字符串转换为数据包，UDP传输使用
  DatagramPacket StringToPacket(String message,InetAddress ip,int port){
       int length = message.length();
       byte buf[] = new byte[length];
       buf = message.getBytes();
       DatagramPacket rdp = new DatagramPacket(buf,0,length,ip,port);
       return rdp;
  }
   String PacketToString(DatagramPacket dp){
        int length = dp.getLength();
        byte buf[] = new byte[length];
        buf = dp.getData();
        String str = new String(buf,0,length);
        return str;
   }
}