Configuring a Life Cycle Callback Listener Method on an Entity Listener Class of a JPA Entity

You can designate an entity listener method on an entity listener class of a JPA entity as a life cycle callback method.

To configure a life cycle callback listener method on an entity listener class, you must do the following:

1. Create an entity listener class.

   This can be any POJO class.

2. Implement the life cycle callback listener method in the entity listener class.

   Callback methods defined on a JPA entity listener class have the following signature:

   void <METHOD>(Object)
   

   You may specify an argument type of Object or the type of the JPA entity class that you will associate the entity listener class with.

3. Associate a life cycle event with the callback listener method.

   You may associate a life cycle event with one and only one callback listener method, but you may associate a given callback listener method with more than one life cycle event.

   For more information, see the following:

   • "Using Annotations"

4. Associate the interceptor class with your JPA entity.

   For more information, see the following:

   • "Using Annotations"

For more information, see the following:

• "What is the JPA Entity Life Cycle?"

• "Life Cycle Callback Listener Methods on a JPA Entity Listener Class"

Using Annotations

You can specify a JPA entity listener method as a life cycle callback method using any of the following annotations:

• @PrePersist

• @PostPersist

• @PreRemove

• @PostRemove

• @PreUpdate

• @PostUpdate

• @PostLoad

Example 7-31 shows how to use the @PostConstruct and @PreDestroy annotation to specify JPA entity listener methods myPostConstruct and myPreDestroy as life cycle callback methods, respectively.

Example 7-31 @PrePersist Life Cycle Listener Callback Method

public class MyProjectEntityListener {
    ...
    @PostConstruct
    public void myPostConstruct (Project obj) { // or just Object
        ...
    }
 
    @PreDestroy
    public void myPreDestroy (Project obj)  { // or just Object
        ...
    }
}

You can associate an entity listener class with a JPA entity using the @EntityListeners annotation. Example 7-32 shows how to associate the entity listener class from Example 7-31 with a JPA entity class.

Note that the life cycle method for @PrePersist is a method of the JPA entity class itself (for more information, see "Configuring a Life Cycle Callback Method on a JPA Entity").

Example 7-32 Associating an Entity Listener Class With a JPA Entity

@Entity
@EntityListeners(MyProjectEntityListener.class)
@Table(name="EJB_PROJECT")
public class Project implements Serializable {
    ...
    @Id
    @Column(name="PROJECT_ID", primaryKey=true)
    public Integer getId() {
        return id;
    }

    ...

    @PrePersist
    public int initialize() {
        ...
    }
}