springboot集成websocket给前端推送消息

一般通常情况下，我们都是前端主动朝后端发送请求，那么有没有可能，后端主动给前端推送消息呢？这时候就可以借助websocket来实现。下面给出一个简单的实现样例。

首先创建一个websocketDemo工程，该工程的整体结构如下：

（1）修改POM文件，增加相关依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.mycompany</groupId><artifactId>websocketDemo</artifactId><version>1.0-SNAPSHOT</version><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.18</version><relativePath/></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-websocket</artifactId></dependency></dependencies></project>

（2）新增application.properties文件，增加端口配置信息，并设置端口为8085

server.port=8085

（3）新增socket处理器MyWebSocketHandler

package com.mycompany.handler;import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;@Component
public class MyWebSocketHandler extends TextWebSocketHandler {private static final Map<String, WebSocketSession> sessions = new ConcurrentHashMap<>();@Overridepublic void afterConnectionEstablished(WebSocketSession session) {System.out.println("连接建立");sessions.put(session.getId(), session);}@Overridepublic void afterConnectionClosed(WebSocketSession session, CloseStatus status) {System.out.println("连接关闭");sessions.remove(session.getId());}public void sendToAll(String message) {sessions.forEach((id, session) -> {if (session.isOpen()) {try {session.sendMessage(new TextMessage(message));} catch (Exception e) {System.out.println("出现异常，原因" + e);sessions.remove(id);}} else {sessions.remove(id);}});}
}

（5）新增socket配置类

package com.mycompany.config;import com.mycompany.handler.MyWebSocketHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;@Configuration
@EnableWebSocket
public class WebsocketConfig implements WebSocketConfigurer {@Autowiredprivate MyWebSocketHandler myWebSocketHandler;@Overridepublic void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {registry.addHandler(myWebSocketHandler, "/ws").setAllowedOrigins("*");}}

（6）新增控制器类，我们编写了一个接口，用来触发推消息的功能，也就当调用/api/push接口时，就会给浏览器推送消息，推送的消息内容为msg字段的值

package com.mycompany.controller;import com.mycompany.handler.MyWebSocketHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class PushController {@Autowiredprivate MyWebSocketHandler myWebSocketHandler;@GetMapping("/api/push")public String push(String msg) {myWebSocketHandler.sendToAll(msg);return "推送成功";}}

（7）编写启动类WebsocketApplication

package com.mycompany;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class WebsocketApplication {public static void main(String[] args) {SpringApplication.run(WebsocketApplication.class, args);}
}

（8）编写一个index.html页面，注意其中的端口需要和application.properties中的端口保持一致

<!DOCTYPE html>
<script>
const socket = new WebSocket('ws://localhost:8085/ws');
socket.onmessage = (e) => {console.log('收到推送:', e.data);document.getElementById('msg').innerHTML += e.data + '<br>';
};
</script>
<div id="msg"></div>

（9）验证测试。首先启动项目WebsocketApplication，然后通过浏览器打开index.html页面