tcp的心跳检测 java 详细实例代码

当使用TCP协议进行网络通信时，心跳检测是一种常见的机制，用于检测连接是否仍然有效。下面是一个基于Java的TCP心跳检测的详细实例代码：

import java.io.*;
import java.net.*;
import java.util.*;

public class TCPHeartbeat {
    private static final int SERVER_PORT = 8888;
    private static final int HEARTBEAT_INTERVAL = 5000; // 心跳间隔，单位为毫秒
    private static final int HEARTBEAT_TIMEOUT = 15000; // 心跳超时时间，单位为毫秒
    
    private static volatile boolean running = true;

    public static void main(String[] args) {
        startServer();
        startClient();
    }

    private static void startServer() {
        new Thread(() -> {
            try {
                ServerSocket serverSocket = new ServerSocket(SERVER_PORT);
                System.out.println("服务器已启动，等待客户端连接...");

                while (running) {
                    Socket clientSocket = serverSocket.accept();
                    System.out.println("客户端已连接：" + clientSocket.getRemoteSocketAddress());

                    // 创建一个新线程处理客户端连接
                    new Thread(() -> {
                        try {
                            BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                            PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

                            long lastHeartbeatTime = System.currentTimeMillis();

                            while (running) {
                                // 读取客户端发送的数据
                                String inputLine = in.readLine();
                                if (inputLine != null) {
                                    System.out.println("客户端消息：" + inputLine);
                                    // 向客户端发送响应数据
                                    out.println("收到消息：" + inputLine);
                                }

                                long currentTime = System.currentTimeMillis();
                                if (currentTime - lastHeartbeatTime > HEARTBEAT_TIMEOUT) {
                                    System.out.println("心跳超时，断开与客户端的连接：" + clientSocket.getRemoteSocketAddress());
                                    break;
                                }
                            }

                            // 关闭连接
                            in.close();
                            out.close();
                            clientSocket.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }).start();
                }

                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }).start();
    }

    private static void startClient() {
        new Thread(() -> {
            try {
                Socket socket = new Socket("localhost", SERVER_PORT);
                System.out.println("已连接到服务器：" + socket.getRemoteSocketAddress());

                BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

                Timer timer = new Timer();

                // 发送心跳消息
                TimerTask heartbeatTask = new TimerTask() {
                    @Override
                    public void run() {
                        out.println("Heartbeat");
                    }
                };

                // 监听心跳超时
                TimerTask timeoutTask = new TimerTask() {
                    @Override
                    public void run() {
                        System.out.println("心跳超时，断开与服务器的连接：" + socket.getRemoteSocketAddress());
                        running = false;
                        timer.cancel();
                    }
                };

                timer.schedule(heartbeatTask, 0, HEARTBEAT_INTERVAL);
                timer.schedule(timeoutTask, HEARTBEAT_TIMEOUT);

                while (running) {
                    // 读取服务器的响应数据
                    String response = in.readLine();
                    if (response != null) {
                        System.out.println("服务器响应：" + response);
                    }
                }

                // 关闭连接
                in.close();
                out.close();
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }).start();
    }
}

以上代码中，我们使用了一个简单的心跳消息 "Heartbeat" 进行通信。服务器端会定时检测客户端的心跳时间，若超过设定的超时时间，就会断开与客户端的连接。客户端则会定时发送心跳消息，同时监听服务器的心跳超时。

希望这个示例代码能帮到你！如果还有其他问题，请随时提问。