当用户连接到Spring WebSocket时如何向用户发送消息

Question

我想在用户连接到Spring WebSocket时向其发送消息，

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {

    @Autowired
    private GenervicSerice<User> userService;
    @Autowired 
    private SimpMessagingTemplate template; 
    private CurrentUser currnetUser;
    @Override
    public void registerStompEndpoints(StompEndpointRegistry stompEndpointRegistry) {
        // TODO Auto-generated method stub
        stompEndpointRegistry.addEndpoint("/ws").withSockJS();
    }

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/queue/", "/topic/", "/exchange/");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void configureClientInboundChannel(ChannelRegistration registration) {

        registration.setInterceptors(myChannelInterception());
        try {
            updateNotificationAndBroadcast();

        } catch (Exception e) {
            return;
        }
    }

    @Bean
    public MyChannelInterception myChannelInterception() {
        return new MyChannelInterception();
    }


    private void updateNotificationAndBroadcast() {    
        try {               
            template.convertAndSend("/queue/notify", "Greetings");
        } catch (Exception e) {
            System.out.println("Error message is " + e.getMessage() + "\n\n\n" + "Caused by " + e.getCause()
                    );
        }

    }

}

MyChannelInterception类为

public class ImtehanChannelInterception extends ChannelInterceptorAdapter {

    private CurrentUser currnetUser;

    @Override
    public Message<?> preSend(Message<?> message, MessageChannel channel) {

        MessageHeaders headers = message.getHeaders();
        SimpMessageType type = (SimpMessageType) headers.get("simpMessageType");
        String simpSessionId = (String) headers.get("simpSessionId");
        currnetUser = new CurrentUser();
        if (type == SimpMessageType.CONNECT) {
            Principal principal = (Principal) headers.get("simpUser");
            currnetUser.setCurrentUserEmail(principal.getName());
            System.out.println("WsSession " + simpSessionId
                    + " is connected for user " + principal.getName());
        } else if (type == SimpMessageType.DISCONNECT) {
            System.out.println("WsSession " + simpSessionId
                    + " is disconnected");
        }

        return message;
    }

}

通过这一点，我在收到新连接的用户，但该方法的信息updateNotificationAndBroadcast()中WebSocketConfig不将消息发送到新的登录用户。

Answer 1

我将创建SessionSubscribeEvent侦听器并SimpMessagingTemplate在内部使用。

顺便说一句，configureClientInboundChannel仅被调用一次（不适用于每个连接的用户）。因此，您必须处理拦截器中的发送消息。

尝试这样的事情：

@Service
public class SomeSubscribeListener {

    private SimpMessagingTemplate template;

    @Autowired
    public SomeSubscribeListener(SimpMessagingTemplate template) {
        this.template = template;
    }

    @EventListener
    public void handleSubscribeEvent(SessionSubscribeEvent event) {
        template.convertAndSendToUser(event.getUser().getName(), "/queue/notify", "GREETINGS");
    }
}

我希望这个能帮上忙