SpringBoot：websocket 实现后端主动前端推送数据

简单说明下websocket实用场景。

• 实时通信领域：
• 社交聊天弹幕
• 多玩家游戏
• 协同编辑
• 股票基金实时报价
• 体育实况更新
• 视频会议/聊天
• 基于位置的应用
• 在线教育
• 智能家居等需要高实时性的场景

一、服务端代码

pom.xml：

<dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId></dependency><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>5.1.0</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>2.0.22</version></dependency></dependencies>

config： 

package com.king.websocket.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;/**
* <b>Function: </b> todo
* @program: WebSocketConfig
* @Package: com.king.websocket.config
* @author: dingcho
* @date: 2025/01/20
* @version: 1.0
* @Copyright: 2025 www.kingbal.com Inc. All rights reserved.
*/
@Configuration
public class WebSocketConfig {@Beanpublic ServerEndpointExporter serverEndpointExporter(){return new ServerEndpointExporter();}}

socket核心代码 - WebSocketServer：

package com.king.websocket.server;import cn.hutool.core.util.StrUtil;
import cn.hutool.log.Log;
import cn.hutool.log.LogFactory;
import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONObject;
import org.springframework.stereotype.Component;import jakarta.websocket.*;
import jakarta.websocket.server.PathParam;
import jakarta.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;/*** <b>Function: </b> todo** @program: WebSocketServer* @Package: com.king.websocket.server* @author: dingcho* @date: 2025/01/20* @version: 1.0* @Copyright: 2025 www.kingbal.com Inc. All rights reserved.*/
@ServerEndpoint("/dev-api/websocket/{userId}")
@Component
public class WebSocketServer {static Log log = LogFactory.get(WebSocketServer.class);// 静态变量，用来记录当前在线连接数private static int onlineCount = 0;// 存放每个客户端对应的MyWebSocket对象private static ConcurrentHashMap<String, WebSocketServer> webSocketMap = new ConcurrentHashMap<>();// 与某个客户端的连接会话，需要通过它来给客户端发送数据private Session session;// 接收userIdprivate String userId = "";/*** 连接建立成功调用的方法* @param session* @param userId*/@OnOpenpublic void onOpen(Session session, @PathParam("userId") String userId) {this.session = session;this.userId = userId;if (webSocketMap.containsKey(userId)) {webSocketMap.remove(userId);webSocketMap.put(userId, this);} else {webSocketMap.put(userId, this);addOnlineCount();}log.info("用户连接:" + userId + ",当前在线人数为:" + getOnlineCount());try {sendMessage("连接成功");} catch (IOException e) {log.error("用户:" + userId + ",网络异常!!!!!!");}}/*** 连接关闭调用的方法*/@OnClosepublic void onClose() {if (webSocketMap.containsKey(userId)) {webSocketMap.remove(userId);//从set中删除subOnlineCount();}log.info("用户退出:" + userId + ",当前在线人数为:" + getOnlineCount());}/*** 收到客户端消息后调用的方法* @param message 客户端发送过来的消息* @param session*/@OnMessagepublic void onMessage(String message, Session session) {log.info("用户消息:" + userId + ",报文:" + message);//可以群发消息//消息保存到数据库redisif (!StrUtil.isEmpty(message)) {try {//解析发送的报文JSONObject jsonObject = JSON.parseObject(message);} catch (Exception e) {log.error("用户:" + userId + ", 接收报文异常!!!!!!");}}}/*** 会话异常* @param session* @param error*/@OnErrorpublic void onError(Session session, Throwable error) {log.error("用户错误:" + this.userId + ",原因:" + error.getMessage());}/*** 实现服务器主动推送*/public void sendMessage(String message) throws IOException {this.session.getBasicRemote().sendText(message);}/*** 实现服务器主动推送*/public static void sendAllMessage(String message) throws IOException {ConcurrentHashMap.KeySetView<String, WebSocketServer> userIds = webSocketMap.keySet();for (String userId : userIds) {WebSocketServer webSocketServer = webSocketMap.get(userId);webSocketServer.session.getBasicRemote().sendText(message);System.out.println("webSocket实现服务器主动推送成功 userId >> " + userId);}}/*** 发送自定义消息*/public static void sendInfo(String message, @PathParam("userId") String userId) throws IOException {log.info("发送消息到:" + userId + "，报文:" + message);if (!StrUtil.isEmpty(message) && webSocketMap.containsKey(userId)) {webSocketMap.get(userId).sendMessage(message);} else {log.error("用户" + userId + ",不在线！");}}public static synchronized int getOnlineCount() {return onlineCount;}public static synchronized void addOnlineCount() {WebSocketServer.onlineCount++;}public static synchronized void subOnlineCount() {WebSocketServer.onlineCount--;}}

定时器 - WebSocketController：

package com.king.websocket.controller;import com.alibaba.fastjson2.JSONObject;
import com.king.websocket.server.WebSocketServer;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.HashMap;
import java.util.Map;/*** <b>Function: </b> todo** @program: WebSocketController* @Package: com.king.websocket.controller* @author: dingcho* @date: 2025/01/20* @version: 1.0* @Copyright: 2025 www.kingbal.com Inc. All rights reserved.*/
@RestController
@RequestMapping("/message")
public class WebSocketController {// 设置定时十秒一次@Scheduled(cron = "0/10 * * * * ?")@PostMapping("/send")public String sendMessage() throws Exception {Map<String, Object> map = new HashMap<>();// 获取当前日期和时间LocalDateTime nowDateTime = LocalDateTime.now();DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");System.out.println(dateTimeFormatter.format(nowDateTime));map.put("server_time", dateTimeFormatter.format(nowDateTime));map.put("server_code", "200");map.put("server_message", "服务器消息来了！！！");JSONObject jsonObject = new JSONObject(map);WebSocketServer.sendAllMessage(jsonObject.toString());return jsonObject.toString();}}

启动项 - WebsocketApplication：

package com.king.websocket;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.scheduling.annotation.EnableScheduling;/*** <b>Function: </b> todo** @program: WebsocketApplication* @Package: com.king.websocket* @author: dingcho* @date: 2025/01/20* @version: 1.0* @Copyright: 2025 www.kingbal.com Inc. All rights reserved.*/
@EnableScheduling
@ServletComponentScan
@SpringBootApplication
public class WebsocketApplication {public static void main(String[] args) {SpringApplication.run(WebsocketApplication.class, args);}}

然后启动项目使用 在线websocket测试-在线工具-postjson 进行测试

直接发送信息服务端，服务端也会接收到信息

二、前端

公共js：WebsocketTool.js

//在JavaScript中实现WebSocket连接失败后3分钟内尝试重连3次/*** @param {string} url  Url to connect* @param {number} maxReconnectAttempts Maximum number of times* @param {number} reconnect Timeout* @param {number} reconnectTimeout Timeout**/
class WebSocketReconnect {constructor(url, maxReconnectAttempts = 3, reconnectInterval = 20000, maxReconnectTime = 180000) {this.url = urlthis.maxReconnectAttempts = maxReconnectAttemptsthis.reconnectInterval = reconnectIntervalthis.maxReconnectTime = maxReconnectTimethis.reconnectCount = 0this.reconnectTimeout = nullthis.startTime = nullthis.socket = nullthis.connect()}// 连接操作connect() {console.log('connecting...')this.socket = new WebSocket(this.url)// 连接成功建立的回调方法this.socket.onopen = () => {console.log('WebSocket Connection Opened!')this.clearReconnectTimeout()this.reconnectCount = 0}// 连接关闭的回调方法this.socket.onclose = (event) => {console.log('WebSocket Connection Closed:', event)this.handleClose()}// 连接发生错误的回调方法this.socket.onerror = (error) => {console.error('WebSocket Connection Error:', error)// 重连this.handleClose()}}//断线重连操作handleClose() {if (this.reconnectCount < this.maxReconnectAttempts && (this.startTime === null || Date.now() - this.startTime < this.maxReconnectTime)) {this.reconnectCount++console.log(`正在尝试重连 (${this.reconnectCount}/${this.maxReconnectAttempts})次...`)this.reconnectTimeout = setTimeout(() => {this.connect()}, this.reconnectInterval)if (this.startTime === null) {this.startTime = Date.now()}} else {console.log('超过最大重连次数或重连时间超时，已放弃连接')// 重置连接次数0this.reconnectCount = 0 // 重置开始时间this.startTime = null   }}//清除重连定时器clearReconnectTimeout() {if (this.reconnectTimeout) {clearTimeout(this.reconnectTimeout)this.reconnectTimeout = null}}// 关闭连接close() {if (this.socket && this.socket.readyState === WebSocket.OPEN) {this.socket.close()}this.clearReconnectTimeout()this.reconnectCount = 0this.startTime = null}
}// WebSocketReconnect 类封装了WebSocket的连接、重连逻辑。
// maxReconnectAttempts 是最大重连尝试次数。
// reconnectInterval 是每次重连尝试之间的间隔时间。
// maxReconnectTime 是总的重连时间限制，超过这个时间后不再尝试重连。
// reconnectCount 用于记录已经尝试的重连次数。
// startTime 用于记录开始重连的时间。
// connect 方法用于建立WebSocket连接，并设置相应的事件监听器。
// handleClose 方法在WebSocket连接关闭或发生错误时被调用，根据条件决定是否尝试重连。
// clearReconnectTimeout 方法用于清除之前设置的重连定时器。
// close 方法用于关闭WebSocket连接，并清除重连相关的状态。// 使用示例
// const webSocketReconnect = new WebSocketReconnect('ws://your-websocket-url')
// 当不再需要WebSocket连接时，可以调用close方法
// webSocketReconnect.close();export default WebSocketReconnect

 三、需要使用到websocket页面

<template><div><el-input v-model="textarea1" :rows="5" type="textarea" placeholder="请输入" /></div>
</template><script setup>
import { ref, reactive,, onMounted, onUnmounted } from 'vue'
import WebSocketReconnect from '@/util/WebsocketTool'// --------------------------------------------
let textarea1 = ref('【消息】---->')
let websocket = null
// 判断当前浏览器是否支持WebSocket
if ('WebSocket' in window) {// 连接WebSocket节点websocket = new WebSocketReconnect('ws://127.0.0.1:8080' + '/dev-api/websocket/123456')
} else {alert('浏览器不支持webSocket')
}// 接收到消息的回调方法
websocket.socket.onmessage = function (event) {let data = event.dataconsole.log('后端传递的数据:' + data)// 数据渲染至页面textarea1.value = textarea1.value + data + '
' + '【消息】---->'
}
// 当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
window.onbeforeunload = function () {websocket.close()
}
// 关闭连接
function closeWebSocket() {websocket.close()
}
// 发送消息
function send() {websocket.socket.send({ myRes: 123 })
}//------------------------------------
</script><style scoped></style>