我正在尝试使用 Stomp 和 Sockjs 创建一个独立的 Java 应用程序作为今年 Spring 的 websocket 客户端，考虑到 spring 规范和 spring-portafolio 示例，我收到此错误：
15:18:01.342 [main] DEBUG com.example.client.WebSocketClientTest - Connecting to : ws://localhost:8080/socket/hello
15:18:01.541 [WebSocketClient-AsyncIO-1] ERROR com.example.client.MyStompSessionHandler - Transport error
org.springframework.messaging.simp.stomp.ConnectionLostException: Connection closed
at org.springframework.messaging.simp.stomp.DefaultStompSession.afterConnectionClosed(DefaultStompSession.java:483) [spring-messaging-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.socket.messaging.WebSocketStompClient$WebSocketTcpConnectionHandlerAdapter.afterConnectionClosed(WebSocketStompClient.java:354) [spring-websocket-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.socket.sockjs.client.AbstractClientSockJsSession.afterTransportClosed(AbstractClientSockJsSession.java:321) [spring-websocket-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.socket.sockjs.client.WebSocketTransport$ClientSockJsWebSocketHandler.afterConnectionClosed(WebSocketTransport.java:172) [spring-websocket-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.socket.adapter.standard.StandardWebSocketHandlerAdapter.onClose(StandardWebSocketHandlerAdapter.java:141) [spring-websocket-4.3.2.RELEASE.jar:4.3.2.RELEASE]...
我在java客户端的代码是：
StandardWebSocketClient webSocketClient = new StandardWebSocketClient();
List<Transport> transports = new ArrayList<>();
transports.add(new WebSocketTransport(webSocketClient));
SockJsClient sockJsClient = new SockJsClient(transports);
ThreadPoolTaskScheduler taskScheduler = new ThreadPoolTaskScheduler();
taskScheduler.afterPropertiesSet();
String stompUrl = "ws://localhost:8080/socket/hello";
WebSocketStompClient stompClient = …