eventlisteners using hibernate 4.0 with spring 3.1.0.release?

Question

These jars are both new released and have the latest solutions for Java EE applications. But I have a problem on specifiying hibernate listeners in hibernate.cfg.xml.

Answer 1

When appending custom Event listeners via the EventListenerRegistry class as mentioned in above responses one needs to make sure the default event listeners are removed. Otherwise if in your application there is onetomany mapping then "Hibernate exception: shared references to the collection: xyz" exception will be thrown

Answer 2

The new approach is to use an Integrator to register the event listeners. Hibernate will now use service discovery for registering event listeners and here is how I got it to work using a maven archetype-webapp

create a file under META-INF/services (which should reside under your resources directory) called org.hibernate.integrator.spi.Integrator with all classes that implement the hibernate spi Interface, one line each. Short example below:

...

META-INF/services/org.hibernate.integrator.spi.Integrator

com.example.CustomIntegrator

com.example.CustomIntegrator

package com.example;

import ...;

public void CustomIntegrator implements Integrator {

    static final Logger logger = LoggerFactory.getLogger(CustomIntegrator.class);

    @Override
    public void integrate(Configuration configuration, SessionFactoryImplementor implementor, SessionFactoryServiceRegistry registry) {
        final EventListenerRegistry eventRegistry = registry.getService(EventListenerRegistry.class);

        logger.info("Registering event listeners");
        // you can add duplication strategory for duplicate registrations
        ...

        // prepend to register before or append to register after
        // this example will register a persist event listener
        eventRegistry.prependListeners(EventType.PERSIST, myListener);
        ...
    }

    ...

}

com.example.MyListener

package com.example;

import ...

public class MyListener implements PersistEventListener {

    static final Logger logger = LoggerFactory.getLogger(MyListener.class);

    public void onPersist(PersistEvent event) throws HibernateException {
        logger.debug("Entering MyListener");

        if(event.getObject() instanceof MyPersistableEntity) {
            MyPersistableEntity entity = (MyPersistableEntity) event.getObject();
            // do something with entity
            ...
        }
    }

    ...
}

Any entity that needs to have this event registered to it must implement MyPersistableEntity (not shown here)

Answer 3

I had the same frustrating problem. Hibernate 4 appears to have fundamentally changed the way you register for events and the Spring group has not yet caught up. Here's my annotation-based solution using an init method to register a listener:

@Component
public class HibernateEventWiring {

    @Autowired
    private SessionFactory sessionFactory;

    @Autowired
    private SomeHibernateListener listener;

    @PostConstruct
    public void registerListeners() {
        EventListenerRegistry registry = ((SessionFactoryImpl) sessionFactory).getServiceRegistry().getService(
        EventListenerRegistry.class);
        registry.getEventListenerGroup(EventType.POST_COMMIT_INSERT).appendListener(listener);
        registry.getEventListenerGroup(EventType.POST_COMMIT_UPDATE).appendListener(listener);
    }
}

An interceptor would be another fine approach, but support for interceptors was mistakenly dropped: https://jira.springsource.org/browse/SPR-8940

Answer 4

You might wanna check the Hibernate Ticket [1]: https://hibernate.onjira.com/browse/HHH-6945

The migration guide says:

hibernate.cfg.xml no longer supported as means of specifying listeners. New approach invloves using an org.hibernate.integrator.spi.Integrator which works based on "service discovery".

And you can get the complete instructions @ http://in.relation.to/Bloggers/EventListenerRegistration

The links in the ticket have some issue, use the following:

https://github.com/hibernate/hibernate-orm/blob/master/hibernate-envers/src/main/java/org/hibernate/envers/event/EnversIntegrator.java

https://github.com/hibernate/hibernate-orm/blob/master/hibernate-envers/src/main/resources/META-INF/services/org.hibernate.integrator.spi.Integrator

Hope this helps someone looking answers for this problem.