SpringBoot ~ 整合WebSocket

1. 添加pom依赖

   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-websocket</artifactId>
   </dependency>
   

2. 添加配置

   @Configuration
   public class WebSocketConfig {
       @Bean
       public ServerEndpointExporter serverEndpointExporter() {
           return new ServerEndpointExporter();
       }
   }
   

3. 编写WebSocket映射类

   @ServerEndpoint(value = "/socket")
   @Controller
   public class WebSocketController implements Serializable {
       //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 CopyOnWriteArraySet<WebSocketController> webSocketSet = new CopyOnWriteArraySet<WebSocketController>();
   
       //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;
   
       /**
        * 连接建立成功调用的方法*/
       @OnOpen
       public void onOpen(Session session) {
           System.out.println(session.getAsyncRemote());
           this.session = session;
           webSocketSet.add(this);     //加入set中
           addOnlineCount();           //在线数加1
           System.out.println("有新连接加入！当前在线人数为" + getOnlineCount());
           sendMessage("wsyjlly");
       }
   
       /**
        * 连接关闭调用的方法
        */
       @OnClose
       public void onClose() {
           webSocketSet.remove(this);  //从set中删除
           subOnlineCount();           //在线数减1
           System.out.println("有一连接关闭！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){
           System.out.println("来自客户端的消息:" + message);
           //群发消息
           sendInfo(session.getId());
       }
   
       /**
        * 发生错误时调用
        * @OnError
        **/
       public void onError(Session session, Throwable error) {
           System.out.println("发生错误");
           error.printStackTrace();
       }
   
   
       private void sendMessage(String message) {
           this.session.getAsyncRemote().sendText(message);
       }
   
   
       /**
        * 群发自定义消息
        * */
       private static void sendInfo(String message){
           for (WebSocketController item : webSocketSet) {
               item.sendMessage(message);
           }
       }
   
       public static synchronized int getOnlineCount() {
           return onlineCount;
       }
   
       public static synchronized void addOnlineCount() {
           WebSocketController.onlineCount++;
       }
   
       public static synchronized void subOnlineCount() {
           WebSocketController.onlineCount--;
       }
   }
   

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