Java實(shí)現(xiàn)Socket服務(wù)端與客戶端雙向通信功能

更新時間：2025年04月09日 11:16:09 作者：kimloner

大家好,由于工作上業(yè)務(wù)的需要,在java項(xiàng)目中引入了socket通信,特此記錄一下,用以備份,本文章中的socket通信實(shí)現(xiàn)了,服務(wù)端與客戶端的雙向通訊,以及二者之間的心跳通信,服務(wù)端重啟之后,客戶端的自動重連功能,需要的朋友可以參考下

原理

Socket通信是計(jì)算機(jī)網(wǎng)絡(luò)中常用的一種通信機(jī)制，它是基于TCP/IP協(xié)議實(shí)現(xiàn)的，提供了兩個應(yīng)用程序之間通過網(wǎng)絡(luò)進(jìn)行數(shù)據(jù)交換的能力。Socket本質(zhì)上是一種抽象概念，為網(wǎng)絡(luò)服務(wù)提供了一組API接口。

Socket通信模型

Socket通信模型通常包括客戶端和服務(wù)器端兩部分。服務(wù)器端：負(fù)責(zé)在特定的端口監(jiān)聽來自客戶端的連接請求，當(dāng)一個請求到達(dá)時，服務(wù)器會與客戶端建立連接，并為客戶端提供相應(yīng)的服務(wù)。客戶端：主動向服務(wù)器的特定IP地址和端口發(fā)起連接請求，連接成功后，客戶端可以通過建立的連接向服務(wù)器發(fā)送請求并接收響應(yīng)。

Socket通信過程

Socket通信過程一般包括以下幾個步驟：

服務(wù)器監(jiān)聽：

服務(wù)器通過socket()函數(shù)創(chuàng)建一個Socket，并通過bind()函數(shù)將其綁定到一個IP地址和端口上。然后，服務(wù)器調(diào)用listen()函數(shù)開始監(jiān)聽該端口上的連接請求。

客戶端請求連接：

客戶端也通過socket()函數(shù)創(chuàng)建一個Socket，然后調(diào)用connect()函數(shù)嘗試與服務(wù)器的指定IP地址和端口建立連接。

服務(wù)器接受連接：

服務(wù)器在接收到客戶端的連接請求后，通過accept()函數(shù)接受這個連接。如果成功，accept()函數(shù)會返回一個新的Socket（通常稱為“子Socket”），用于與該客戶端進(jìn)行通信。

數(shù)據(jù)傳輸：連接建立成功后，客戶端和服務(wù)器就可以通過新建立的Socket進(jìn)行數(shù)據(jù)傳輸了。數(shù)據(jù)傳輸可以是單向的也可以是雙向的。應(yīng)用程序可以使用send(), write(), recv(), read()等函數(shù)進(jìn)行數(shù)據(jù)發(fā)送和接收操作。

斷開連接：

當(dāng)通信結(jié)束后，客戶端和服務(wù)器都可以調(diào)用close()函數(shù)來關(guān)閉自己持有的Socket，從而斷開兩者之間的連接。 TCP vs UDP 在實(shí)際使用中，基于Socket的通信方式主要有兩種：基于TCP和基于UDP。 TCP Socket：提供可靠、面向連接、基于字節(jié)流的通信方式。適用對數(shù)據(jù)完整性和順序有要求的應(yīng)用場景。 UDP Socket：提供無連接、不保證可靠性、基于消息（數(shù)據(jù)報(bào)）的通信方式。適用于對實(shí)時性要求高、容忍部分?jǐn)?shù)據(jù)丟失或亂序的應(yīng)用場景。

代碼實(shí)現(xiàn)

服務(wù)端

服務(wù)端主體邏輯：和每個接入的客戶端都會使用獨(dú)立線程建立起長連接，二者之間使用心跳保持聯(lián)系，使用clientSockets 存儲了每個客戶端的信息便于和客戶端建立起聯(lián)系。

package com.example.demo2.server.socket;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Map;
import java.util.concurrent.*;

/**
 * @author kim
 */
@Component
public class TcpServer implements DisposableBean {
    private static final Logger logger = LoggerFactory.getLogger(TcpServer.class);

    private final SocketServerConfig config;
    private ServerSocket serverSocket;
    private ExecutorService executorService;
    private volatile boolean running = true;

    // 存儲客戶端連接
    private final Map<String, Socket> clientSockets = new ConcurrentHashMap<>();

    public TcpServer(SocketServerConfig config) {
        this.config = config;
    }

    @PostConstruct
    public void start() throws IOException {
        executorService = Executors.newFixedThreadPool(config.getMaxThreads());
        serverSocket = new ServerSocket(config.getPort());
        logger.info("平臺socket服務(wù)已啟動, 監(jiān)聽端口為 {}", config.getPort());

        new Thread(this::acceptConnections).start();
    }

    private void acceptConnections() {
        while (running) {
            try {
                Socket clientSocket = serverSocket.accept();
                String clientAddress = clientSocket.getInetAddress().getHostAddress();
                clientSockets.put(clientAddress, clientSocket);
                executorService.execute(new ClientHandler(clientSocket, clientAddress));
            } catch (IOException e) {
                if (running) {
                    logger.error("Connection accept error", e);
                }
            }
        }
    }

    // 用于發(fā)送消息到特定客戶端
    public void sendMessageToClient(String clientAddress, String message) throws IOException {
        Socket socket = clientSockets.get(clientAddress);
        if (socket != null && !socket.isClosed()) {
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            out.println(message);
            logger.info("Sent message to {}: {}", clientAddress, message);
        } else {
            logger.warn("Client {} is not connected or socket is closed", clientAddress);
        }
    }

    @Override
    public void destroy() throws Exception {
        running = false;
        executorService.shutdown();
        for (Socket socket : clientSockets.values()) {
            if (!socket.isClosed()) {
                socket.close();
            }
        }
        if (serverSocket != null && !serverSocket.isClosed()) {
            serverSocket.close();
        }
        logger.info("TCP Server stopped");
    }

    private class ClientHandler implements Runnable {
        private final Socket clientSocket;
        private final String clientAddress;

        ClientHandler(Socket socket, String address) {
            this.clientSocket = socket;
            this.clientAddress = address;
        }

        @Override
        public void run() {
            try (BufferedReader in = new BufferedReader(
                    new InputStreamReader(clientSocket.getInputStream()));
                 PrintWriter out = new PrintWriter(
                         clientSocket.getOutputStream(), true)) {
                logger.info("Client connected: {}", clientAddress);
                String input;
                while ((input = in.readLine()) != null) {
                    logger.debug("Received: {}", input);
                    out.println(input);
                    logger.info("Client connected: {}", clientAddress);
                }
            } catch (IOException e) {
                logger.warn("Client connection closed: {}", e.getMessage());
            } finally {
                try {
                    clientSockets.remove(clientAddress);
                    clientSocket.close();
                } catch (IOException e) {
                    logger.error("Error closing socket", e);
                }
            }
        }


    }
}

配置類

package com.example.demo2.server.socket;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix = "socket.server")
@Data
public class SocketServerConfig {
    private int port;
    private int maxThreads;
    
    // Getters and Setters
}

配置文件

server:
  port: 8080

socket:
  server:
    port: 8088
    maxThreads: 50

向客戶端發(fā)送測試信息

 @GetMapping("/send")
    public String sendMessage(String clientAddress) throws IOException {
       tcpServer.sendMessageToClient("192.168.3.8","77777777777");
       return "success";
    }

服務(wù)端發(fā)送日志

客戶端

客戶端主體邏輯，使用自己設(shè)計(jì)的心跳機(jī)制，監(jiān)聽服務(wù)端狀態(tài)，如果服務(wù)端斷開連接，則客戶端會嘗試重新建立聯(lián)系。

package com.example.demo1.socketclient;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Service;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;

@Service
public class TcpClientService implements ApplicationRunner, DisposableBean {
    private static final Logger logger = LoggerFactory.getLogger(TcpClientService.class);

    private final SocketClientConfig config;
    private Socket socket;
    private PrintWriter out;
    private BufferedReader in;
    private final AtomicBoolean running = new AtomicBoolean(true);
    private final ExecutorService executor = Executors.newSingleThreadExecutor();
    private final MessageListener messageListener;

    @Autowired
    public TcpClientService(SocketClientConfig config, MessageListener messageListener) {
        this.config = config;
        this.messageListener = messageListener;
    }

    @Override
    public void run(ApplicationArguments args) throws Exception {
        initializeConnection();
    }

    @Override
    public void destroy() throws Exception {
        running.set(false);
        closeResources();
        executor.shutdown();
    }

    private synchronized void initializeConnection() {
        new Thread(() -> {
            while (running.get()) {
                try {
                    socket = new Socket();
                    socket.setKeepAlive(true);
                    socket.setSoTimeout(config.getHeartbeatTimeout());
                    socket.connect(new InetSocketAddress(config.getHost(), config.getPort()), config.getTimeout());

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

                    logger.info("Connected to server {}:{}", config.getHost(), config.getPort());

                    executor.execute(this::listenToServer);

                    startHeartbeat();

                    while (!socket.isClosed() && socket.isConnected()) {
                        Thread.sleep(1000);
                    }
                } catch (Exception e) {
                    logger.warn("Connection error: {}", e.getMessage());
                } finally {
                    closeResources();
                    if (running.get()) {
                        logger.info("Attempting to reconnect in 5 seconds...");
                        sleepSafely(5000);
                    }
                }
            }
        }, "tcp-client-connector").start();
    }

    private void listenToServer() {
        try {
            String response;
            while (running.get() && !socket.isClosed()) {
                try {
                    response = in.readLine();
                    if (response == null) {
                        logger.warn("Server closed connection");
                        break; // 終止循環(huán)，表示連接已關(guān)閉
                    }
                    logger.debug("Received server message: {}", response);
                    messageListener.onMessage(response);
                } catch (SocketTimeoutException e) {
                    logger.debug("Socket read timeout");
                } catch (IOException e) {
                    if (!socket.isClosed()) {
                        logger.warn("Connection lost: {}", e.getMessage());
                        break; // 終止循環(huán)，表示連接已中斷
                    }
                }
            }
        } finally {
            closeResources(); // 確保資源關(guān)閉
        }
    }

    private void startHeartbeat() {
        new Thread(() -> {
            while (running.get() && !socket.isClosed()) {
                try {
                    sendMessageInternal("HEARTBEAT");
                    sleepSafely(config.getHeartbeatInterval());
                } catch (Exception e) {
                    logger.warn("Heartbeat failed: {}", e.getMessage());
                    break;
                }
            }
        }, "heartbeat-thread").start();
    }

    public synchronized void sendMessage(String message) throws IOException {
        if (socket == null || !socket.isConnected()) {
            throw new IOException("Not connected to server");
        }
        out.println(message);
        logger.debug("Sent message: {}", message);
    }

    private synchronized void sendMessageInternal(String message) {
        try {
            if (socket != null && socket.isConnected()) {
                out.println(message);
            }
        } catch (Exception e) {
            logger.warn("Failed to send heartbeat");
        }
    }

    private synchronized void closeResources() {
        try {
            if (out != null) out.close();
            if (in != null) in.close();
            if (socket != null) socket.close();
        } catch (IOException e) {
            logger.warn("Error closing resources: {}", e.getMessage());
        }
    }

    private void sleepSafely(long millis) {
        try {
            Thread.sleep(millis);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    public interface MessageListener {
        void onMessage(String message);
    }
}

消息監(jiān)聽：監(jiān)聽服務(wù)發(fā)送的消息

package com.example.demo1.socketclient;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

@Component
public class ServerMessageHandler implements TcpClientService.MessageListener {
    private static final Logger logger = LoggerFactory.getLogger(ServerMessageHandler.class);

    @Override
    public void onMessage(String message) {
       if(StringUtils.isNotEmpty(message)){
           if (!message.contains("HEARTBEAT")){
               //處理其他邏輯
               System.out.println("接收服務(wù)端消息成功："+message);
           }else{
               //心跳消息
               System.out.println(message);
           }
       }
    }


}

配置類

package com.example.demo1.socketclient;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConfigurationProperties(prefix = "socket.client")
@Data
public class SocketClientConfig {
    private String host;
    private int port;
    private int timeout;
    private int heartbeatInterval;
    private int heartbeatTimeout;

    // Getters and Setters
}

發(fā)送測試方法

 @GetMapping("/send")
    public ResponseEntity<String> sendMessage() {
        try {
            tcpClient.sendMessage("客戶端發(fā)送信息");
            return ResponseEntity.ok("Message sent");
        } catch (IOException e) {
            return ResponseEntity.status(503).body("Server unavailable");
        }
    }

配置文件

socket:
  client:
    host: 192.168.3.8 #服務(wù)端ip地址
    port: 8088 #監(jiān)聽端口
    timeout: 5000
    heartbeat-interval: 3000    # 心跳間隔30秒
    heartbeat-timeout: 6000     # 心跳超時60秒
server:
  port: 8082

客戶端發(fā)送信息后，服務(wù)端會接收到信息。