一个UDP通信案例

Bertha 。 2024-03-17 22:45 77阅读 0赞

## 一个UDP通信案例 ##

### 需要的依赖 ###

<dependency>
    	<groupId>cn.hutool</groupId>
    	<artifactId>hutool-all</artifactId>
    	<version>5.7.8</version>
    </dependency>

### UDP服务器端案例 ###

package cn.demo.udp;
    
    import cn.hutool.cache.CacheUtil;
    import cn.hutool.cache.impl.TimedCache;
    import cn.hutool.core.date.DateUtil;
    import cn.hutool.core.lang.Console;
    
    import java.io.IOException;
    import java.net.*;
    import java.util.Scanner;
    import java.util.Timer;
    import java.util.TimerTask;
    
    public class UdpServerTest {
        
    
        //定时缓存,默认1秒过期
        private static final TimedCache<String, String> timedCache = CacheUtil.newTimedCache(2000);
    
        public static void main(String[] args) throws IOException {
        
            //每5秒清空一次timedCache
            timedCache.schedulePrune(5000);
            //UDP是无连接的，没有像TCP那样的建立连接和保持状态的机制
            //因此这里引入定时缓存，来记录和判断当前可能在线的udp-client
            Timer timer = new Timer();
            timer.schedule(new TimerTask() {
        
                @Override
                public void run() {
        
                    Console.log("[{}]------当前可能在线的udp-client-----start--", DateUtil.now());
                    if (timedCache.keySet().size() > 0) {
        
                        for (String s : timedCache.keySet()) {
        
                            Console.log("------" + s);
                        }
                    }
                    Console.log("[{}]--------------------------------end--", DateUtil.now());
                }
            }, 1000, 4000);
    
    
            //创建一个udp服务器端口为7788的DatagramSocket
            DatagramSocket socket = new DatagramSocket(7788);
    
            //定义UDP数据包的缓冲区 和 DatagramPacket
            byte[] buffer = new byte[1024 * 64];
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
    
            while (true) {
        
                //连续监听,等待接收客户端发送的UDP数据包
                socket.receive(packet);
    
                //解析 客户端发送的UDP数据包
                int length = packet.getLength();
                String recStr = new String(buffer, 0, length);
                String ip = packet.getAddress().getHostAddress(); //192.168.81.123
                int port = packet.getPort(); //2000
                String netAddr = ip + ":" + port;
                timedCache.put(netAddr, "udp-cli"); //引入定时缓存，来记录和判断当前服务器可能在线的udp-client
                Console.log("[{}] rec-from:{},msg:{}", DateUtil.now(), netAddr, recStr);
    
    
                if ("aaa".equals(recStr)) {
        
                    byte[] sendBytes = "bbb!".getBytes();
                    socket.send(new DatagramPacket(sendBytes,
                            sendBytes.length,
                            packet.getAddress(),
                            port));
    
                } else if ("exit".equals(recStr)) {
        
                    byte[] sendBytes = "ok!".getBytes();
                    socket.send(new DatagramPacket(sendBytes,
                            sendBytes.length,
                            packet.getAddress(),
                            port));
                    Console.log("[{}] {}要主动下线...", DateUtil.now(), netAddr);
                    timedCache.remove(netAddr);
                } else {
        
                    byte[] sendBytes = "not-correct-req-data!!!".getBytes();
                    socket.send(new DatagramPacket(sendBytes,
                            sendBytes.length,
                            packet.getAddress(),
                            port));
                }
            }
    
    
    
        }
    }

### UDP客户端案例 ###

package cn.demo.udp;
    
    import cn.hutool.core.date.DateUtil;
    import cn.hutool.core.lang.Console;
    
    import java.io.IOException;
    import java.net.*;
    import java.util.Scanner;
    
    public class UdpClientTest {
        
        public static void main(String[] args) throws IOException {
        
            DatagramSocket socket = new DatagramSocket();
            Scanner sc = new Scanner(System.in);
    
    
            while (true){
        
                //------------向udp服务器端发送信息-----------------------------------
                System.out.println("请输入要发送的消息:");
                String input = sc.nextLine();
    
                //发送报文到7788端口
                byte[] bytes = input.getBytes();
                DatagramPacket packet = new DatagramPacket(bytes, bytes.length,
                        InetAddress.getLocalHost(), 7788);
                socket.send(packet);
                if ("exit".equals(input)){
        
                    System.out.println("udp cli主动下线...");
                    socket.close();
                    break;
                }
    
                //------------接收udp服务器返回的消息------------------------
                //定义UDP数据包的缓冲区 和 DatagramPacket
                byte[] buffer = new byte[1024 * 64];
                DatagramPacket packetServerRec = new DatagramPacket(buffer, buffer.length);
    
    
                //连续监听,等待接收客户端发送的UDP数据包
                socket.receive(packetServerRec);
                //解析 客户端发送的UDP数据包
                int length = packetServerRec.getLength();
                String recStr = new String(buffer, 0, length);
                String ip = packetServerRec.getAddress().getHostAddress(); //192.168.81.123
                int port = packetServerRec.getPort(); //2000
                String netAddr = ip + ":" + port;
                Console.log("[{}] rec-from-udp-server:{},msg:{}", DateUtil.now(), netAddr, recStr);
    
            }
    
    
        }
    }