由于要做app的UDP協議交互，所以就特地學習了下，其實也就類似于java的server和socket，下面就寫了個簡單的demo

服務端：

package com.test1;import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetSocketAddress;import java.net.SocketException;public class UpdServer {    PRivate byte[] buff = new byte[1024];    private DatagramPacket dp;    private DatagramSocket ds;    private InetSocketAddress socketAddress;    public UpdServer(String host, int port){        socketAddress = new InetSocketAddress(host, port);        try {            ds = new DatagramSocket(socketAddress);        } catch (SocketException e) {            System.out.println("連接失敗:" + e.getLocalizedMessage());            e.printStackTrace();        }        System.out.println("服務器開啟監聽...");    }        private String receive(String host, int port) {        String info = "";        try{            dp = new DatagramPacket(buff, 0, buff.length);            ds.receive(dp);            info = new String(dp.getData(), 0, dp.getLength());        }catch (Exception e) {            e.printStackTrace();        }        return info;    }        public static void main(String[] args) {        String host = "127.0.0.1";        int port = 8888;        UpdServer server = new UpdServer(host, port);        String info = server.receive(host, port);        System.out.println(info);        //發送信息到客服端        server.send(new String("你好，騷年！"));    }    private void send(String string) {        DatagramPacket dps = new DatagramPacket(buff, 0, buff.length, dp.getAddress(), dp.getPort());        dps.setData(string.getBytes());        try {            ds.send(dps);        } catch (IOException e) {            e.printStackTrace();        }    }}

客戶端：

package com.test1;import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;import java.net.SocketException;public class UpdClient {    private byte[] buff = new byte[1024];    private DatagramPacket dp;    private DatagramSocket ds;    public UpdClient(){        try {            ds = new DatagramSocket();        } catch (SocketException e) {            e.printStackTrace();        }    }        public static void main(String[] args) {        UpdClient updClient = new UpdClient();        String host = "127.0.0.1";        int port = 8888;        updClient.send(host, port, new String("你好，少年!").getBytes());                //接受        String info = updClient.receive();        System.out.println(info);    }    private String receive() {        DatagramPacket dpr = new DatagramPacket(buff, buff.length);        String info = "";        try {            ds.receive(dpr);            info = new String(dpr.getData(), 0, dpr.getLength());        } catch (IOException e) {            e.printStackTrace();        }        return info;    }    private void send(String host, int port, byte[] b) {        try{            dp = new DatagramPacket(buff, 0, buff.length, InetAddress.getByName(host), port);            dp.setData(b);            ds.send(dp);        }catch (Exception e) {            e.printStackTrace();        }    }}