Java Socket编程之UDP

public class UDPServer {
    public static void main(String[] args) throws IOException {
        /*
         * 接收客户端发送的数据
         */
        //1.创建服务器端DatagramSocket，指定端口
        DatagramSocket socket=new DatagramSocket(8888);
        System.out.println("服务器端已经启动，等待客户端发送数据");
        while(true){
            //2.创建数据报，用于接收客户端发送的数据
            byte[] data=new byte[1024];//创建字节数组指定接收的数据包大小
            DatagramPacket packet=new DatagramPacket(data, data.length);
            //3.接收客户端发送的数据
            socket.receive(packet);//此方法在接收到数据报之前一直处于阻塞状态
            UDPThread udpthread=new UDPThread(packet,socket);
            udpthread.start();
        }
        }
}

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

/*
 * 客户端
 */
public class UDPClient {
    public static void main(String[] args) throws IOException {
        /*
         * 向服务器端发送数据
         */
        //1.定义服务器的地址、端口号、数据
        InetAddress address=InetAddress.getByName("localhost");
        int port=8800;
        byte[] data="用户名：admin;密码：123".getBytes();
        //2.创建数据报，包含发送的数据信息
        DatagramPacket packet=new DatagramPacket(data, data.length, address, port);
        //3.创建DatagramSocket对象
        DatagramSocket socket=new DatagramSocket();
        //4.向服务器端发送数据报
        socket.send(packet);
       /*
         * 接收服务器端响应的数据
         */
        //1.创建数据报，用于接收服务器端响应的数据
        byte[] data2=new byte[1024];
        DatagramPacket packet2=new DatagramPacket(data2, data2.length);
        //2.接收服务器响应的数据
        socket.receive(packet2);
        //3.读取数据
        String reply=new String(data2, 0, packet2.getLength());
        System.out.println("我是客户端，服务器说："+reply);
        //4.关闭资源
        socket.close();
    }
}

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketException;

public class UDPThread extends Thread {
    DatagramPacket packet=null; 
    DatagramSocket socket=null;
    public UDPThread(DatagramPacket packet,DatagramSocket socket){
        this.packet=packet;
        this.socket=socket;
    }
    public  void run() {
            try {
                //4.读取数据
                String info=new String(packet.getData(), 0, packet.getLength());
                System.out.println("我是服务器，客户端说："+info);
                /*
                 * 向客户端响应数据
                 */
                //1.定义客户端的地址、端口号、数据
                InetAddress address=packet.getAddress();
                int port=packet.getPort();
                byte[] bytes="欢迎您".getBytes();
                //2.创建数据报，包含响应的数据信息
                DatagramPacket packet2=new DatagramPacket(bytes, bytes.length, address, port);
                //3.响应客户端
                socket.send(packet2);
            } catch (IOException e) {
                e.printStackTrace();
            }
            //socket.close();不能关闭 
    }
}