9 UDP 消息发送

没有客户端和服务端这一说法

package Internet;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

// UDP：类似发短信
  // 发送端
public class Test09_UDP_User1 {
    public static void main(String[] args) throws Exception {
        // 1.建一个Socket
        DatagramSocket socket = new DatagramSocket();
        // 2.建一个包裹
        String msg="msg";
        InetAddress local = InetAddress.getByName("127.0.0.1");
        int port=8888;
           // 建一个包裹的主要部分
        DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.length(),local,port);
        // 3.发送包裹
        socket.send(packet);
        // 4.关闭
        socket.close();
    }
}

//////////////////////////////////
package Internet;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

  //接收端
public class Test09_UDP_User2 {
    public static void main(String[] args) throws Exception {
        // 1.建一个Socket
        DatagramSocket socket = new DatagramSocket(8888);
        // 2.建一个新的包裹，接收传输过来的东西 packet2装下packet
        byte[] buffer = new byte[1024];
        DatagramPacket packet2 = new DatagramPacket(buffer,0,buffer.length);
        // 3.接收发过来的包裹 packet2装下packet
        socket.receive(packet2);
           // 验证包裹
        System.out.println(new String(packet2.getData(),0,packet2.getLength()));
        // 4.关闭
        socket.close();
    }
}