java - 如何使用 Spring 实现自定义 WebSocket 子协议(protocol)

Question

我必须在 Spring Boot 应用程序中添加对自定义 WebSocket 子协议(protocol)(因此不是 STOMP)的支持，但我很难理解我需要提供什么以及 Spring 已经拥有什么。

这就是我走了多远:

@Configuration
@EnableWebSocket
public class WebSocketAutoConfiguration implements WebSocketConfigurer {

    public void registerWebSocketHandlers(WebSocketHandlerRegistry webSocketHandlerRegistry) {
        webSocketHandlerRegistry.addHandler(this.webSocketHandler(), new String[]{endpointUrl});
    }

    @Bean
    public WebSocketHandler webSocketHandler() {
        ExecutorSubscribableChannel clientInboundChannel = new ExecutorSubscribableChannel();
        ExecutorSubscribableChannel clientOutboundChannel = new ExecutorSubscribableChannel();
        SubProtocolWebSocketHandler subProtocolWebSocketHandler = new SubProtocolWebSocketHandler(clientInboundChannel, clientOutboundChannel);
        subProtocolWebSocketHandler.addProtocolHandler(new SubProtocolHandler() {
            public List<String> getSupportedProtocols() {
                return Collections.singletonList("custom-protocol");
            }

            public void handleMessageFromClient(WebSocketSession session, WebSocketMessage<?> message, MessageChannel outputChannel) throws Exception {
                session.sendMessage(new TextMessage("some message"));
            }

            public void handleMessageToClient(WebSocketSession session, Message<?> message) throws Exception {
            }

            public String resolveSessionId(Message<?> message) {
                return UUID.randomUUID().toString();
            }

            public void afterSessionStarted(WebSocketSession session, MessageChannel outputChannel) throws Exception {
                System.out.println("SESSION STARTED");
            }

            public void afterSessionEnded(WebSocketSession session, CloseStatus closeStatus, MessageChannel outputChannel) throws Exception {
                session.close();
                System.out.println("SESSION ENDED");
            }
        });
        return subProtocolWebSocketHandler;
    }
}

从某种意义上说，这是可行的，handleMessageFromClient确实在网络套接字消息上触发，但我无法理解MessageChannel outputChannel和handleMessageToClient<的目的.

是否可以使用 SubProtocolWebSocketHandler 获取 PerConnectionWebSocketHandler 语义？

与此相关的文档基本上不存在，例如handleMessageToClient 的文档说:

Handle the given {@link Message} to the client associated with the given WebSocket session.

嗯，太棒了。而且 STOMP 实现令人难以置信，因此它们作为指南不太有用。

任何例子，广泛的步骤或任何东西，真的，将不胜感激。

Answer 1

事实证明这非常简单。根本不需要搞乱 SubProtocolWebSocketHandler 。唯一的要求是提供的 WebSocketHandler 实现 SubProtocolCapable。

public class CustomHandler implements WebSocketHandler, SubProtocolCapable {
   ...
}

仅此而已。要创建 PerConnectionWebSocketHandler，只需扩展它并实现 SubProtocolCapable 就足够了:

public class CustomHandler extends PerConnectionWebSocketHandler implements SubProtocolCapable {
   ...
}