STOMP客户端Java Spring-不调用handleFrame，而是调用get PayloadType

Question

我在Spring框架中对STOMP有问题。我的代码与端点连接，并接收消息，但它仅调用getPeyloadType，但不调用handleFrame。我也不例外你能帮助我吗 ？下面是我的代码

我尝试将getPayloadType和StringMessageConvert的返回类型更改为ByteArray。

public WebSocketCl (String Uri, Logger log) {

        this.url = new String (Uri);

        webSocketClient = new StandardWebSocketClient();
        stompClient = new WebSocketStompClient(webSocketClient);
        stompClient.setMessageConverter(new StringMessageConverter());
        sessionHandler = new MySessionHandler();
        stompClient.connect(url, sessionHandler);

        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   

    }

和处理程序类：

public class MySessionHandler extends StompSessionHandlerAdapter {

    private StompSession sessionCon;
    private StompFrameHandler handler;

    @Override
    public void afterConnected(StompSession session, StompHeaders connectedHeaders) {
        System.out.println("Connected");
        this.sessionCon = session;
        this.sessionCon.subscribe("/listen", handler = new StompFrameHandler() {
            @Override
            public Type getPayloadType(StompHeaders headers) {
                System.out.println("type");
                return String.class;
            }

            @Override
            public void handleFrame(StompHeaders headers, Object payload) {
                String json = new String((byte[]) payload);
                System.out.println(json);
                System.out.println("received");
            }

        });
        this.sessionCon.send("/hal/sensor/3", "{}");

    }
}