websocket暫時能想到的應用是瀏覽器聊天和後臺日誌實時顯示到前臺。

當後臺啟動程式後，等待前臺連線，連線上之後，前後臺就可以相互發送資料了。

先貼上pom配置：

<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>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>webjars-locator</artifactId>
        </dependency
 
>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>sockjs-client</artifactId>
            <version>1.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
 

            <artifactId>stomp-websocket</artifactId>
            <version>2.3.3</version>
        </dependency>
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.1.0</version>
        </dependency>

websocket配置類

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");//配置客戶端訂閱字首
        config.setApplicationDestinationPrefixes("/app");//配置客戶端傳送訊息路徑字首
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        //"/gs-guide-websocket"是前臺連線的端點url
        registry.addEndpoint("/gs-guide-websocket").withSockJS();
    }

}

java伺服器端推送用例

@Component
public class WebSocketTemplate {
    private SimpMessagingTemplate messagingTemplate;

    @Autowired
    public WebSocketTemplate(SimpMessagingTemplate messagingTemplate) {
        this.messagingTemplate = messagingTemplate;
    }
    //向訂閱了 /topic/hello 客戶端websocket例項傳送資料
    public void sendMessage(String message){
        messagingTemplate.convertAndSend("/topic/hello","hello,client");
    }
}

伺服器端接收客戶端傳送的訊息並反饋

@Controller
public class GreetingController {


    @MessageMapping("/hello")
    @SendTo("/topic/hello")
    public String greeting(String message) throws Exception {
        Thread.sleep(1000); // simulated delay
        return "Hello, client! I get your message";
    }

}

客戶端需要的

<script src="/webjars/jquery/jquery.min.js"></script>
<script src="/webjars/sockjs-client/sockjs.min.js"></script>
<script src="/webjars/stomp-websocket/stomp.min.js"></script>

var stompClient = null;
    //連線到伺服器    
    function connect() {
    var socket = new SockJS('/gs-guide-websocket');
    stompClient = Stomp.over(socket);
    stompClient.connect({}, function (frame) {
        console.log('Connected: ' + frame);
        //接收服務端傳送給/topic/greetings的訂閱訊息
        stompClient.subscribe('/topic/greetings', function (greeting) {
            console.log(greeting);
            JSON.parse(greeting.body);//解析json字串為物件
        });
    });
    //斷開連線
    function disconnect() {
    if (stompClient !== null) {
        stompClient.disconnect();
    }
    //向伺服器傳送訊息
    function sendHello() {
    stompClient.send("/app/hello", {}, "hello server");
}

}
}

存在的問題：
客戶端重新整理後沒有斷開連線的話，伺服器再次傳送資料給客戶端會接收到兩次訊息。
如果有了解的，希望指教一下。