org.bushe.swing.event.annotation

Annotation Type EventTopicSubscriber

@Retention(value=RUNTIME)
@Target(value=METHOD)
public @interface EventTopicSubscriber

An Annotation for subscribing to EventService Topics.

This annotation simplifies much of the repetitive boilerplate used for subscribing to EventService Topics.

Instead of this:

 public class MyAppController implements EventTopicSubscriber {
   public MyAppController {
      EventBus.subscribe("AppClosing", this);
   }
   public void onEvent(String topic, Object data) {
      JComponent source = (JComponent)data;
      //do something
   }
 }
 

You can do this:

 public class MyAppController {  //no interface necessary
   public MyAppController {
       AnnotationProcessor.process(this);//this line can be avoided with a compile-time tool or an Aspect
   }
   @EventTopicSubscriber{topic="AppClosingEvent"}
   public void onAppClosing(String topic, Object data) {
      //do something
   }
 }
 

That's pretty good, but when the controller does more, annotations are even nicer.

 public class MyAppController implements EventTopicSubscriber {
   public MyAppController {
      EventBus.subscribe("AppStartingEvent", this);
      EventBus.subscribe("AppClosingEvent", this);
   }
   public void onEvent(String topic, Object data) {
      //wicked bad pattern, but we have to this
      //...or create multiple subscriber classes and hold instances of them fields, which is even more verbose...
      if ("AppStartingEvent".equals(topic)) {
         onAppStartingEvent((JComponent)data);
      } else ("AppClosingEvent".equals(topic)) {
         onAppClosingEvent((JComponet)data);
      }

   }

   public void onAppStartingEvent(JComponent requestor) {
      //do something
   }

   public void onAppClosingEvent(JComponent requestor) {
      //do something
   }
 }
 

Instead of all that, you can do this:

 public class MyAppController {
   public MyAppController {
       AnnotationProcessor.process(this);//this line can be avoided with a compile-time tool or an Aspect
   }
   @EventTopicSubscriber{topic="AppStartingEvent"}
   public void onAppStartingEvent(Object data) {
      //do something
   }
   @EventTopicSubscriber{topic="AppClosingEvent"}
   public void onAppClosingEvent(Foo data) {
      //do something
   }
 }
 

Brief, clear, and easy.

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
String	topic The topic to subscribe to

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
Class<? extends EventService>	autoCreateEventServiceClass Whether or not to autocreate the event service if it doesn't exist on subscription, default is true.
String	eventServiceName The event service to subscribe to, default to the EventServiceLocator.SERVICE_NAME_EVENT_BUS.
int	priority Determines the order in which this subscriber is called, default is FIFO.
ReferenceStrength	referenceStrength Whether to subscribe weakly or strongly.

Element Detail

topic

public abstract String topic

The topic to subscribe to

referenceStrength

public abstract ReferenceStrength referenceStrength

Whether to subscribe weakly or strongly.

Default:

org.bushe.swing.event.annotation.ReferenceStrength.WEAK

eventServiceName

public abstract String eventServiceName

The event service to subscribe to, default to the EventServiceLocator.SERVICE_NAME_EVENT_BUS.

Default:

"EventBus"

priority

public abstract int priority

Determines the order in which this subscriber is called, default is FIFO.

Default:

0

autoCreateEventServiceClass

public abstract Class<? extends EventService> autoCreateEventServiceClass

Whether or not to autocreate the event service if it doesn't exist on subscription, default is true. If the service needs to be created, it must have a default constructor.

Default:

org.bushe.swing.event.ThreadSafeEventService.class