基于UDP的Socket通信

Socket除了支持TCP协议，也支持UDP协议。

编码

SocketServerUDP

package com.ispeasant.socket.udp;

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

public class SocketServerUDP {
    public static void main(String[] args) {

        try {
            // UDP方式，采用的是DatagramSocket，与TCP是有点不一样
            DatagramSocket udpSocket = new DatagramSocket(8888);
            System.out.println("----UDP服务端启动----");

            // UDP方式，接收客户端发送过来的数据，也是有点不一样
            DatagramPacket packetClient = null;
            byte[] dataClient = null;

            // 为了更方便测试，我们让服务端程序一直启动
            while (true) {
                // 设定数据包的大小
                dataClient = new byte[1024];
                packetClient = new DatagramPacket(dataClient, dataClient.length);

                // 接收数据
                udpSocket.receive(packetClient);

                // 采用多线程来处理数据
                Thread thread = new Thread(new SocketThreadUDP(udpSocket, packetClient));
                thread.start();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }


    }
}

SocketThreadUDP

package com.ispeasant.socket.udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.text.SimpleDateFormat;
import java.util.Date;

public class SocketThreadUDP implements Runnable {
    DatagramSocket socketUDP = null;
    DatagramPacket packetUDP = null;

    public SocketThreadUDP(DatagramSocket socketUDP, DatagramPacket packetUDP) {
        this.socketUDP = socketUDP;
        this.packetUDP = packetUDP;
    }

    @Override
    public void run() {
        // 客户端发过来的信息,是通过从packet里获取
        String info = new String(packetUDP.getData(), 0, packetUDP.getLength());

        // 加个时间戳，更好区分
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd 'at' HH:mm:ss z");
        Date date = new Date(System.currentTimeMillis());

        System.out.println(date + "客户端：" + info);

        // 因为采用的是UDP方式，不像TCP那样有握手建立通信通道，所以我们向客户端返回信息时，是需要制定ip和端口
        // 而这ip和端口信息，是可以通过packet来获取
        // 向客户端发送信息
        String server2Client = "我是服务端" + date;
        byte[] data = server2Client.getBytes();
        try {
            socketUDP.send(new DatagramPacket(data, data.length, packetUDP.getAddress(), packetUDP.getPort()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

SocketClientUDP

package com.ispeasant.socket.udp;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.text.SimpleDateFormat;
import java.util.Date;

public class SocketClientUDP {
    public static void main(String[] args) {
        // 发送给服务端的信息
        String info = "你好，我是客户端";
        byte[] data = info.getBytes();

        try {
            // 通过packet来打包数据发送给服务端
            DatagramPacket clientPacket = new DatagramPacket(data, data.length, InetAddress.getByName("localhost"), 8888);
            // 通过DatagramSocket负责与服务端通信
            DatagramSocket socket = new DatagramSocket();
            socket.send(clientPacket);

            // 向服务端发送完数据后，我们可以看看服务端有没有信息返回给我们
            byte[] serverData = new byte[1024];
            DatagramPacket serverPacket = new DatagramPacket(serverData, serverData.length);
            socket.receive(serverPacket);

            // 接收到的服务端信息
            String server2Client = new String(serverData,0,serverPacket.getLength());

            // 加个时间戳，更好区分
            SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd 'at' HH:mm:ss z");
            Date date = new Date(System.currentTimeMillis());

            System.out.println(date + ",服务端：" + server2Client);

            // 关闭sokcet
            socket.close();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}