Problem statement:
What is the Adobe Experience Manager recommended way to create a Listener?
Requirement:
Adobe provides a Framework service registry that allows EventHandler objects to be registered and notified when an event is sent or posted. This article explains the recommended way to create a Listener to handle events on the property in Adobe.
Introduction:
- EventHandler objects are registered with the Framework service registry and are notified with an Event object when an event is sent or posted.
- EventHandler objects can inspect the received Event object to determine its topic and properties.
- EventHandler objects must be registered with a service property EventConstants.EVENT_TOPIC whose value is the list of topics in which the event handler is interested.
Listener:
Create Component Service with Event Handler class and implement Event Handler class Provide event topic for the action
Override handle event method
package com.mysite.core.listeners;
import org.apache.sling.api.SlingConstants;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.propertytypes.ServiceDescription;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventConstants;
import org.osgi.service.event.EventHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
@Component(service = EventHandler.class,
immediate = true,
property = {
EventConstants.EVENT_TOPIC + "=org/apache/sling/api/resource/Resource/*"
})
@ServiceDescription("Demo to listen on changes in the resource tree")
public class SimpleResourceListener implements EventHandler {
private final Logger logger = LoggerFactory.getLogger(getClass());
public void handleEvent(final Event event) {
logger.debug("Resource event: {} at: {}", event.getTopic(), event.getProperty(SlingConstants.PROPERTY_PATH));
}
}
AEM best practices and development guide 