websocket 概念

websocket 是一个通信协议，通过单个 TCP 连贯提供全双工通信。websocket 连贯胜利后，服务端和客户能够进行双向通信。不同于 http 通信协议须要每次由客户端发动，服务响应到客户端。
websocket 绝对轮询也能节约带宽，并且能实时的进行通信。

整合步骤

1. 增加 maven 依赖

<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>    <version>2.1.3.RELEASE</version></dependency><dependency>        <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-freemarker</artifactId>    <version>2.1.3.RELEASE</version></dependency>

增加web、websocket和freemarker依赖。

2. 应用 ServerEndpointExporter 创立 bean

这个 bean 会主动注册申明 @ServerEndpoint 注解申明的 websocket endpoint，应用springboot自带tomcat启动须要该配置，应用独立 tomcat 则不须要该配置。

@Configurationpublic class WebSocketConfig {    //tomcat启动无需该配置    @Bean    public ServerEndpointExporter serverEndpointExporter() {        return new ServerEndpointExporter();    }}

3. 创立服务端端点 (ServerEndpoint)

@Component@ServerEndpoint(value = "/message")@Slf4jpublic class WebSocket {    private static Map<String, WebSocket> webSocketSet = new ConcurrentHashMap<>();    private Session session;    @OnOpen    public void onOpen(Session session) throws SocketException {        this.session = session;        webSocketSet.put(this.session.getId(),this);        log.info("【websocket】有新的连贯,总数:{}",webSocketSet.size());    }    @OnClose    public void onClose(){        String id = this.session.getId();        if (id != null){            webSocketSet.remove(id);            log.info("【websocket】连贯断开:总数:{}",webSocketSet.size());        }    }    @OnMessage    public void onMessage(String message){        if (!message.equals("ping")){            log.info("【wesocket】收到客户端发送的音讯,message={}",message);            sendMessage(message);        }    }    /**     * 发送音讯     * @param message     * @return 全副都发送一遍     */    public void sendMessage(String message){        for (WebSocket webSocket : webSocketSet.values()) {            webSocket.session.getAsyncRemote().sendText(message);        }        log.info("【wesocket】播送音讯,message={}", message);    }}

4. 增加 controller 和 客户端

  • 增加 controller

    @GetMapping({"","index.html"})public ModelAndView index() {  ModelAndView view = new ModelAndView("index");  return view;}

  • 增加ftl页面

    <!DOCTYPE html><html><head>  <title>websocket</title></head><body><div>  <input type="text" name="message" id="message">  <button id="sendBtn">发送</button></div><div style="width:100px;height: 500px;" id="content"></div><script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.0/jquery.js"></script><script type="text/javascript">  var ws = new WebSocket("ws://127.0.0.1:8080/message");  ws.onopen = function(evt) {      console.log("Connection open ...");  };  ws.onmessage = function(evt) {      console.log( "Received Message: " + evt.data);      var p = $("<p>"+evt.data+"</p>")      $("#content").prepend(p);      $("#message").val("");  };  ws.onclose = function(evt) {      console.log("Connection closed.");  };  $("#sendBtn").click(function(){      var aa = $("#message").val();      ws.send(aa);  })</script></body></html>

5. 展现成果

附录

github源码