UDP （User Datagram Protocol）消息发送

服务器端

package com.haoran.lesson03;

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

public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(9888);


        //将客户端打包的内容放入到buffer字节中 IO流
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        socket.receive(packet);//阻塞接受，真正意义上的接收

        System.out.println(packet.getAddress());
        System.out.println(new String(packet.getData(),0, packet.getLength()));

        socket.close();


    }
}

客户端

package com.haoran.lesson03;

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

public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {

        DatagramSocket socket = new DatagramSocket();

        String msg="hello,Server";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port =9888;

        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length,localhost,port);

        socket.send(packet);
        socket.close();

    }
}