项目引入WebSocket

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/websocket").setAllowedOrigins("*").withSockJS();
    }

}

@RestController
public class GreetingController {
    private final SimpMessagingTemplate simpMessagingTemplate;

    public GreetingController(SimpMessagingTemplate simpMessagingTemplate) {
        this.simpMessagingTemplate = simpMessagingTemplate;
    }

    @MessageMapping("/hello")
    @SendTo("/topic/greetings")
    public Greeting greeting(HelloMessage message) throws Exception {
        System.out.println("Request: get message: " + message);
        return new Greeting("Response: Hello, " + HtmlUtils.htmlEscape(message.getName()) + "!");
    }

    @GetMapping("/broadcast")
    public String sendBroadcastCommand(@RequestParam String command) {
        simpMessagingTemplate.convertAndSend("/topic/broadcast", command);
        return command;
    }
}

<script src="static/js/stomp.min.js"></script>
<script src="static/js/sockjs-1.0.0.min.js"></script>

function watchBroadcast() {
  const socket = new SockJS('/websocket');
  const client = Stomp.over(socket);
  client.connect(
    {},
    () => {
      client.subscribe('/topic/broadcast', res => {
       console.log(res.body)
        });
    }
  );
}