import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.SocketException;

import java.net.UnknownHostException;

import java.util.Stack;

public class MyUDB {

    /**

     * UDP服务端

     * @throws IOException

     */

    public static void UDPserver() throws IOException {

        //1.创建服务器端DatagtamSocket，指定端口号

        DatagramSocket socket = new DatagramSocket(2505);

        //2.创建数据报，用于接收客服端发送的数据

        byte[] data = new byte[1024];//创建字节数组，指定数据报的大小

        DatagramPacket packet = new DatagramPacket(data, data.length);//

        //3.接收客服端发送的消息

        System.out.println("服务器已经启动。。。。。。。。。");

        socket.receive(packet);//此方法在收到数据之前会一直阻塞

        //4.读取数据

        String info = new String(data,0,packet.getLength());

        System.out.println("服务器说"+info);

        /*

         * 响应客服端数据

         * */

        //1.定义客服端的地址、端口号、数据

        InetAddress address = packet.getAddress();

        int port = packet.getPort();

        byte[]  data2 = "欢迎你".getBytes();

        //2.创建数据报，包含响应的数据信息

        DatagramPacket packet2 = new DatagramPacket(data2, data2.length,address,port);

        //3.响应客服端

        socket.send(packet2);

        //4.关闭资源

        socket.close();

    }

    /**

     * UDP客服端

     * @throws IOException

     */

    public static void  UDPclient() throws IOException {

        // 1.定义服务器的地址、端口号、数据

        InetAddress address = InetAddress.getByName("202.202.43.125");

        int port = 2505;

        byte[] data ="我是客服端".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.向服务器发送数据报

        socket.send(packet);

        /*

         * 接收服务器端的数据

         * */

        //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("服务器说:"+reply);

        //4.关闭资源

        socket.close();

    }

}