1、后端引入webSocket

2、配置webSocket服务

xjs-business/xjs-business-warning/pom.xml

@@ -23,6 +23,12 @@
             <artifactId>xjs-business-common</artifactId>
             <version>3.3.0</version>
         </dependency>
+
+        <!-- websocket -->
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-websocket</artifactId>
+        </dependency>
     </dependencies>
 
 </project>

xjs-business/xjs-business-warning/src/main/java/com/xjs/config/WebSocketConfig.java

@@ -0,0 +1,21 @@
+package com.xjs.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.socket.server.standard.ServerEndpointExporter;
+
+/**
+ * websocket配置
+ * @author xiejs
+ * @since 2022-01-13
+ */
+@Configuration
+public class WebSocketConfig {
+    /**
+     * 注入一个ServerEndpointExporter,该Bean会自动注册使用@ServerEndpoint注解申明的websocket endpoint
+     */
+    @Bean
+    public ServerEndpointExporter serverEndpointExporter() {
+        return new ServerEndpointExporter();
+    }
+}

xjs-business/xjs-business-warning/src/main/java/com/xjs/server/WebSocketServer.java

@@ -0,0 +1,145 @@
+package com.xjs.server;
+
+import lombok.extern.log4j.Log4j2;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+
+import javax.websocket.*;
+import javax.websocket.server.PathParam;
+import javax.websocket.server.ServerEndpoint;
+import java.io.IOException;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * api预警websocket
+ *
+ * @author xiejs
+ * @since 2022-01-13
+ */
+@Log4j2
+@ServerEndpoint("warning/api/{userId}")
+@Component
+public class WebSocketServer {
+    /**
+     * 静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
+     */
+    private static int onlineCount = 0;
+    /**
+     * concurrent包的线程安全Set，用来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userId
+     */
+    private String userId = "";
+
+    /**
+     * 连接建立成功调用的方法
+     */
+    @OnOpen
+    public 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);
+            //加入set中
+        } else {
+            webSocketMap.put(userId, this);
+            //加入set中
+            addOnlineCount();
+            //在线数加1
+        }
+
+        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
+     */
+    @OnClose
+    public 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
+     */
+    @OnMessage
+    public 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、redis
+        if (StringUtils.isNotBlank(message)) {
+
+
+            try {
+                session.getBasicRemote().sendText("回复的消息");
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+
+
+        }
+    }
+
+    /**
+     * @param session
+     * @param error
+     */
+    @OnError
+    public void onError(Session session, Throwable error) {
+        log.error("用户错误:" + this.userId + ",原因:" + error.getMessage());
+        error.printStackTrace();
+    }
+
+    /**
+     * 实现服务器主动推送
+     */
+    public void sendMessage(String message) throws IOException {
+        this.session.getBasicRemote().sendText(message);
+    }
+
+
+    /**
+     * 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 (StringUtils.isNotBlank(userId) && 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--;
+    }
+
+}