package com.socket.udp;import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetSocketAddress;import java.net.SocketException;/** * 基于UDP协议通信，服务端程序。 */public class Server{    private DatagramSocket server = null;    private InetSocketAddress addr = null;    private final byte[] buffer = new byte[256];    private DatagramPacket packet = null;    public Server(String host, int port) throws SocketException    {        this.addr = new InetSocketAddress(host, port);        this.server = new DatagramSocket(this.addr);        System.out.println("服务端开启");    }    /**     * 接收     */    public String receive() throws IOException    {        this.packet = new DatagramPacket(this.buffer, this.buffer.length);        this.server.receive(this.packet);        return new String(this.packet.getData(), 0, this.packet.getLength());    }    /**     * 发送     */    public DatagramPacket response(String info) throws IOException    {        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, this.packet.getAddress(), this.packet.getPort());        p.setData(info.getBytes());        this.server.send(p);        return p;    }    public static void main(String[] args) throws IOException    {        String serverHost = "127.0.0.1";        int serverPort = 10000;        Server server = new Server(serverHost, serverPort);        while (true)        {            System.out.println("服务端接收到:" + server.receive());            server.response("server说：客户端你好！");        }    }}

package com.socket.udp;import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;import java.net.UnknownHostException;/** *  基于UDP协议通信，客户端程序。 */public class Client{    private DatagramSocket client = null;    private DatagramPacket packet = null;    private final byte[] buffer = new byte[1024];    public Client(String host, int port, byte[] bytes) throws SocketException, UnknownHostException    {        this.client = new DatagramSocket();        this.packet = new DatagramPacket(bytes, bytes.length, InetAddress.getByName(host), port);        System.out.println("客户端开启");    }    /**     * 发送     */    public DatagramPacket send() throws IOException    {        this.client.send(this.packet);        return this.packet;    }    /**     * 接收     */    public String receive(String host, int port) throws IOException    {        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, InetAddress.getByName(host), port);        this.client.receive(p);        return new String(p.getData());    }    public String receive2() throws IOException    {        DatagramPacket p = new DatagramPacket(this.buffer, this.buffer.length, this.packet.getAddress(), this.packet.getPort());        this.client.receive(p);        return new String(p.getData());    }    public static void main(String[] args) throws IOException    {        String serverHost = "127.0.0.1";        int port = 10000;        Client client = new Client(serverHost, port, "client说：服务器你好！".getBytes());        client.send();        //String info = client.receive(serverHost, port);        System.out.println("客户端接收到:" + client.receive2());    }}