Subscribe to EventQueues

Subscribe to EventQueues

You can subscribe a method (as if in an EventListener) to an EventQueue by annotate it with Subscribe. For example,

@Subscribe("queue1")
public void method1(Event event) {
	// this method will be called when EventQueue "queue1" of Desktop scope is published
	Object data = event.getData();
	Component target = event.getTarget();
}
public void publish() {
	EventQueue<Event> eq = EventQueues.lookup("queue1", EventQueues.DESKTOP, true);
	eq.publish(new Event("onMyEvent", component, data));
}

In the example above, when you publish an event in the EventQueue, the subscribed method will be called. It is a useful mechanism to communicate with other composers. See also

 

EventQueue Scope

You can subscribe to EventQueue of different scope.

@Subscribe(value = "queue2", scope = EventQueues.SESSION)
public void method2(Event event) {
	// this method will be called when EventQueue "queue2" of Session scope is published
}
public void publish() {
	EventQueue<Event> eq = EventQueues.lookup("queue2", EventQueues.SESSION, true);
	eq.publish(new Event("onMyEvent", component, data));
}

Available scopes are: Desktop, Group, Session, Application. Note that Group scope requires ZK EE. See also EventQueues.

 

Subscriber Method Parameter

The method which subscribes to the EventQueue takes either no parameter, or one parameter of type Event.

@Subscribe("queue3")
public void method3() { // the event parameter can be omitted
	// ...
}

Version History

Version	Date	Content
6.0.1	April 2012	@Subscribe was introduced.