Spring 启动 WebSockets TextWebSocketHandler 不适用于 json 消息

Question

I have added web sockets to my app for transmitting messages and make an interactive app.

What I need to transmit with web-sockets is the POJO Objects. But, the TextWebSocketHandler is not working and not sending messages. When I test the web sockets, I get:

WebSocket is already in CLOSING or CLOSED state.

I don't know if it work but I think the size of the messages is stopping the web socket.

Code:

@Configuration
@EnableWebSocket
public class WebsocketConfig implements WebSocketConfigurer{
    @Bean
    public WebSocketHandler myMessageHandler() {
        return new MyMessageHandler();
    }


    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myMessageHandler(), "/my-websocket-endpoint");
    }

}

public class MyMessageHandler extends TextWebSocketHandler {

    @Autowired
    UserRepository userRepository;

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        // The WebSocket has been closed
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        // The WebSocket has been opened
        // I might save this session object so that I can send messages to it outside of this method

        // Let's send the first message
        Gson gson=new Gson();
        session.sendMessage(new TextMessage(gson.toJson(findall())));
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage textMessage) throws Exception {
        // A message has been received

            Gson gson=new Gson();
            session.sendMessage(new TextMessage(gson.toJson(findall())));

    }

    public List<User> findall(){

        return userRepository.findAll();

    }

}

Answer 1

尝试在使用 json 解析的方法中删除 throws Exception，然后在解析操作中应用 try 和 catch 并处理您可能遇到的异常。