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Subscribe to EventQueues

  • Available for ZK:
  • http://www.zkoss.org/product/zkhttp://www.zkoss.org/whyzk/zkeeVersion ee.png

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. This is a useful mechanism to communicate with other composers. See also EventQueue.


 

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.

 

Event Name

Since 7.0.3, you can also listen to a specified event name

@Subscribe(value = "queue2", eventName = "event1")
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.DESKTOP, true);
	eq.publish(new Event("event1", component, data));
}

 

Subscriber Method Parameter

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

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

Since 7.0.3, ZK automatically maps event data into the method parameters in order.

@Subscribe("queue3")
public void method3(int i, String s) { 
	// i will be 100, s will be "eventData"
	// ...
}

public void publish() {
	EventQueue<Event> eq = EventQueues.lookup("queue3", EventQueues.DESKTOP, true);
	eq.publish(new Event("event1", component, new Object[]{100, "eventData"}));
}

If you put the event at the first one, it also works well.

@Subscribe("queue3")
public void method3(Event event, int i, String s) { 
	// ...
}

To recap, we now have four ways to use a parameter:

  • method()
  • method(Event event)
  • method(Event event, int d1, String d2, ....)
  • method(int d1, String d2, ...)

Version History

Last Update : 2014/6/25


Version Date Content
6.0.1 April 2012 @Subscribe was introduced.
7.0.3 June 2014 ZK-2076 Enhance Subscribe annotation to map java method by the event name and the parameter type in order




Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.