Its quite common when you create an application, there is a need to create an audit trail on the application level where all entity insert, update and delete events are logged.

In this post, I would like to describe a simple approach that can help you to avoid littering with unnecessary statements in your application code. The solution is to register a class as a listener on Hibernate events. Once class is triggered, you will be able to write audit information to a database or log file.

The following shows a Hibernate event interceptor class that is triggered when persistent entity is inserted, deleted or updated.

public class HibernateEventInterceptor	implements	PostInsertEventListener,
							PostUpdateEventListener,
							PostDeleteEventListener,
							Initializable {

	public HibernateEventInterceptor() {

	}

	public void initialize(Configuration cfg) {

	}

	public void onPostInsert(PostInsertEvent event) {
		String entityName = event.getPersister().getEntityName();
		System.out.println("Inserted entity: " + entityName);
	}

	public void onPostUpdate(PostUpdateEvent event) {
		String entityName = event.getPersister().getEntityName();
		System.out.println("Updated entity: " + entityName);
	}

	public void onPostDelete(PostDeleteEvent event) {
		String entityName = event.getPersister().getEntityName();
		System.out.println("Deleted entity: " + entityName);
	}
}

The following shows extra configuration that must be added to persistence.xml, in order for the interceptor class to be triggered:

<persistence>
	<persistence-unit name="org.example.demo">
	<jta-data-source>java:/test</jta-data-source>
		<properties>
			.
			.
			.
		<property name="hibernate.ejb.event.post-insert" value="org.example.demo.HibernateEventInterceptor"/>
		<property name="hibernate.ejb.event.post-update" value="org.example.demo.HibernateEventInterceptor"/>
		<property name="hibernate.ejb.event.post-delete" value="org.example.demo.HibernateEventInterceptor"/>
		</properties>
	</persistence-unit>
</persistence>