Java网络编程UDP协议发送接收数据

package net;

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class SendDemo {

  public static void main(String[] args) throws IOException {

   //A

   DatagramSocket ds = new DatagramSocket();

   //B

   byte [] by = "Hello,UDP" .getBytes();

   int length = by.length;

   InetAddress addr = InetAddress.getByName( "192.168.1.22" );

   int port = 10010 ;

   DatagramPacket dp = new DatagramPacket(by, length, addr, port);

   //C

   ds.send(dp);

   //D

   ds.close();

  }

}

package net;

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class ReceiveDemo {

  public static void main(String[] args) throws IOException {

   //A

   DatagramSocket ds = new DatagramSocket( 10010 );

   //B

   byte [] by = new byte [ 1024 ];

   int length = by.length;

   DatagramPacket dp = new DatagramPacket(by, length);

   //C

   ds.receive(dp);

   //D

   //获取对方ip

   InetAddress addr = dp.getAddress();

   String ip = addr.getHostAddress();

   byte [] by2 = dp.getData();

   int len = by2.length;

   String s = new String(by2, 0 , len);

   System.out.println(ip+ "发送的数据是：" +s);

   //E

   ds.close();

  }

}

package net;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class SendDemo {

  public static void main(String[] args) throws IOException {

   //A

   DatagramSocket ds = new DatagramSocket();

   //数据来自键盘录入

   BufferedReader br = new BufferedReader( new InputStreamReader(System.in));

   String line = null ;

   while ((line = br.readLine()) != null ){

    //当输入jieshu时，结束

    if ( "jieshu" .equals(line)){

     break ;

    }

    //B

    byte [] by = line.getBytes();

    int length = by.length;

    InetAddress addr = InetAddress.getByName( "192.168.1.22" );

    int port = 10010 ;

    DatagramPacket dp = new DatagramPacket(by, length, addr, port);

    //C

    ds.send(dp);

   }

   //D

   ds.close();

  }

}

package net;

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

public class ReceiveDemo {

  public static void main(String[] args) throws IOException {

   //A

   DatagramSocket ds = new DatagramSocket( 10010 );

   //多次接受版本

   while ( true ){

    //B

    byte [] by = new byte [ 1024 ];

    int length = by.length;

    DatagramPacket dp = new DatagramPacket(by, length);

    //C

    ds.receive(dp);

    //D

    //获取对方ip

    InetAddress addr = dp.getAddress();

    String ip = addr.getHostAddress();

    byte [] by2 = dp.getData();

    int len = by2.length;

    String s = new String(by2, 0 , len);

    System.out.println(ip+ "发送的数据是：" +s);

   }

   //E

   //ds.close();

  }

}