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package javax.faces.event;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.annotation.Inherited;
/**
* Classes tagged with this annotation are
* installed as listeners using the method {@link
* javax.faces.application.Application#subscribeToEvent} or {@link
* javax.faces.component.UIComponent#subscribeToEvent} (depending on the
* circumstances, described below).
*
*
*
* The default implementation must support attaching this annotation
* to {@link javax.faces.component.UIComponent} or {@link
* javax.faces.render.Renderer} classes. In both cases, the annotation
* processing described herein must commence during the implementation
* of any variant of {@link
* javax.faces.application.Application}.createComponent()
* and must complete before the UIComponent
instance is
* returned from createComponent()
. The annotation
* processing must proceed according to an algorithm semantically
* equivalent to the following.
*
If this annotation is not present on the class in
question, no action must be taken.
Determine the "target" on which to call
subscribeToEvent
.
If the class to which this annotation is attached
implements {@link ComponentSystemEventListener} and is a
UIComponent
instance, "target" is the
UIComponent
instance.
If the class to which this annotation is attached
implements {@link ComponentSystemEventListener} and is a
Renderer
instance, "target" is the
UIComponent
instance that is to be rendered by
this Renderer
instance.
If the class to which this annotation is attached
implements {@link ComponentSystemEventListener} and is neither
an instance of Renderer
nor
UIComponent
, the action taken is
unspecified. This case must not trigger any kind of error.
If the class to which this annotation is attached
implements SystemEventListener
and does not
implement ComponentSystemEventListener
, "target"
is the {@link javax.faces.application.Application}
instance.
-
Determine the variant of subscribeToEvent()
to
call and the parameters to pass to it.
If "target" is a UIComponent
call {@link
javax.faces.component.UIComponent#subscribeToEvent(Class,
ComponentSystemEventListener)}, passing the {@link
#systemEventClass} of the annotation as the first argument and
the instance of the class to which this annotation is attached
(which must implement
ComponentSystemEventListener
) as the second
argument.
If "target" is the {@link
javax.faces.application.Application} instance, inspect the
value of the {@link #sourceClass} annotation attribute value.
If the value is Void.class
, call {@link
javax.faces.application.Application#subscribeToEvent(Class,
SystemEventListener)}, passing the value of {@link
#systemEventClass} as the first argument and the instance of the
class to which this annotation is attached (which must
implement SystemEventListener) as the second
argument.
Otherwise, call {@link
javax.faces.application.Application#subscribeToEvent(Class,
Class, SystemEventListener)}, passing the value of {@link
#systemEventClass} as the first argument, the value of {@link
#sourceClass} as the second argument, and the instance of the
class to which this annotation is attached (which must
implement SystemEventListener) as the third
argument.
*
* Example: The standard renderer for
* javax.faces.resource.Stylesheet
must have the following
* annotation declaration:
* @ListenerFor(systemEventClass=PostAddToViewEvent.class)
* This will cause the renderer to be added as a listener for the
* {@link PostAddToViewEvent} to all components that list it as their
* renderer.
*
*
* @since 2.0
*/
@Retention(value=RetentionPolicy.RUNTIME)
@Target(value=ElementType.TYPE)
@Inherited
@Repeatable(ListenersFor.class)
public @interface ListenerFor {
/**
* The kind of system event for which
* this class will be installed as a listener. The implementation
* only supports exact matches on the Class
and must
* not honor subclass relationships. It is valid to have EL
* Expressions in the value of this attribute, as long as the
* expression resolves to an instance of the expected type.
*
* @return the event class
*/
public Class systemEventClass();
/**
* The kind of object that emits events
* of the type given by the value of the {@link #systemEventClass}
* attribute. It is valid to have EL Expressions in the value of
* this attribute, as long as the expression resolves to an instance
* of the expected type.
*
* @return the source class
*/
public Class sourceClass() default Void.class;
}