This project provides code samples to clarify this tutorial: http://timezra.blogspot.com/2011/10/jpa-callbacks-with-hibernate.html

It is a multi-module Maven project. The code can be compiled and the tests run using standard Maven commands, e.g.,
    $> mvn clean package

The timezra.hibernate.jpa.entity-manager-callbacks sub-project contains sample code for using the Hibernate EntityManager, which automatically ties JPA annotations to Hibernate lifecycle events.

The timezra.hibernate.jpa.event-listener-callbacks sub-project contains sample code for manually configuring the Hibernate SessionFactory to recognize JPA annotations and to bind the annotated methods to Hibernate lifecycle events.