6人参与 • 2025-07-25 • Java
大家好,由于工作上业务的需要,在java项目中引入了socket通信,特此记录一下,用以备份,本文章中的socket通信实现了,服务端与客户端的双向通讯,以及二者之间的心跳通信,服务端重启之后,客户端的自动重连功能。
socket通信是计算机网络中常用的一种通信机制,它是基于tcp/ip协议实现的,提供了两个应用程序之间通过网络进行数据交换的能力。socket本质上是一种抽象概念,为网络服务提供了一组api接口。
socket通信模型通常包括客户端和服务器端两部分。
服务器端:负责在特定的端口监听来自客户端的连接请求,当一个请求到达时,服务器会与客户端建立连接,并为客户端提供相应的服务。
客户端:主动向服务器的特定ip地址和端口发起连接请求,连接成功后,客户端可以通过建立的连接向服务器发送请求并接收响应。
socket通信过程一般包括以下几个步骤:
服务器通过socket()函数创建一个socket,并通过bind()函数将其绑定到一个ip地址和端口上。然后,服务器调用listen()函数开始监听该端口上的连接请求。
客户端也通过socket()函数创建一个socket,然后调用connect()函数尝试与服务器的指定ip地址和端口建立连接。
服务器在接收到客户端的连接请求后,通过accept()函数接受这个连接。如果成功,accept()函数会返回一个新的socket(通常称为“子socket”),用于与该客户端进行通信。
数据传输:连接建立成功后,客户端和服务器就可以通过新建立的socket进行数据传输了。数据传输可以是单向的也可以是双向的。应用程序可以使用send(), write(), recv(), read()等函数进行数据发送和接收操作。
当通信结束后,客户端和服务器都可以调用close()函数来关闭自己持有的socket,从而断开两者之间的连接。
tcp vs udp
在实际使用中,基于socket的通信方式主要有两种:基于tcp和基于udp。
tcp socket:提供可靠、面向连接、基于字节流的通信方式。适用对数据完整性和顺序有要求的应用场景。
udp socket:提供无连接、不保证可靠性、基于消息(数据报)的通信方式。适用于对实时性要求高、容忍部分数据丢失或乱序的应用场景。
服务端主体逻辑:和每个接入的客户端都会使用独立线程建立起长连接,二者之间使用心跳保持联系,使用clientsockets 存储了每个客户端的信息便于和客户端建立起联系。
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; // 存储客户端连接 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("平台socket服务已启动, 监听端口为 {}", 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); } } } } // 用于发送消息到特定客户端 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); } } } } }
配置类
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
向客户端发送测试信息
@getmapping("/send") public string sendmessage(string clientaddress) throws ioexception { tcpserver.sendmessagetoclient("192.168.3.8","77777777777"); return "success"; }
服务端发送日志
客户端接收日志
客户端主体逻辑,使用自己设计的心跳机制,监听服务端状态,如果服务端断开连接,则客户端会尝试重新建立联系。
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; // 终止循环,表示连接已关闭 } 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; // 终止循环,表示连接已中断 } } } } finally { closeresources(); // 确保资源关闭 } } 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); } }
消息监听:监听服务发送的消息
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")){ //处理其他逻辑 system.out.println("接收服务端消息成功:"+message); }else{ //心跳消息 system.out.println(message); } } } }
配置类
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 }
发送测试方法
@getmapping("/send") public responseentity<string> sendmessage() { try { tcpclient.sendmessage("客户端发送信息"); 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 #服务端ip地址 port: 8088 #监听端口 timeout: 5000 heartbeat-interval: 3000 # 心跳间隔30秒 heartbeat-timeout: 6000 # 心跳超时60秒 server: port: 8082
客户端发送信息后,服务端会接收到信息。
以上就是java接入socket通信服务端与客户端的全部代码,二者实现了互相通信,具体的业务场景则需要小伙伴们在此基础上额外的设计逻辑了,有其他疑问或者想要测试demo的可以后台私我,看到会回复。
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