Spring WebSockets@Sendto映射中的路径变量

Question

...
@MessageMapping("/fleet/{fleetId}/driver/{driverId}")
@SendTo("/topic/fleet/{fleetId}")
public Simple simple(@DestinationVariable String fleetId, @DestinationVariable String driverId) {
    return new Simple(fleetId, driverId);
}
...

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig extends AbstractWebSocketMessageBrokerConfigurer {
    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/topic");
        config.setApplicationDestinationPrefixes("/live");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/fleet").withSockJS();
    }
}

index.html

var socket = new SockJS('/fleet');
var stompClient = Stomp.over(socket);
stompClient.connect({}, function(frame) {
    // Doesn't Work
    stompClient.subscribe('/topic/fleet/MyFleet', function(greeting) {
    // Works
    stompClient.subscribe('/topic/fleet/{fleetId}', function(greeting) {
        // Do some stuff
    });
});

发送样品

    stompClient.send("/live/fleet/MyFleet/driver/MyDriver", {}, JSON.stringify({
        // Some simple content
    }));

Answer 1

尽管@messagemapping支持占位符，但它们不会在@sendto目标中公开/解析。目前，无法使用@sendto注释定义动态目的地（请参见问题SPR-12170)。您可以暂时使用SimpMessagingTemplate（这就是它在内部的工作方式）。以下是你应该怎么做：

@MessageMapping("/fleet/{fleetId}/driver/{driverId}")
public void simple(@DestinationVariable String fleetId, @DestinationVariable String driverId) {
    simpMessagingTemplate.convertAndSend("/topic/fleet/" + fleetId, new Simple(fleetId, driverId));
}

在您的代码中，目标'/topic/fleet/{fleetId}‘被视为文字，这就是订阅它的原因，只是因为您发送到了完全相同的目标。

如果您只想发送一些用户特定的初始数据，可以直接在订阅中返回：

@SubscribeMapping("/fleet/{fleetId}/driver/{driverId}")
public Simple simple(@DestinationVariable String fleetId, @DestinationVariable String driverId) {
    return new Simple(fleetId, driverId);
}

@MessageMapping("/fleet/{fleetId}/driver/{driverId}")
@SendTo("/topic/fleet/{fleetId}")
public Simple simple(@DestinationVariable String fleetId, @DestinationVariable String driverId) {
    return new Simple(fleetId, driverId);
}