Callbacks Methods: It is often useful for the application to react to certain events that occur inside the persistence mechanism.
| Type | Description |
|---|---|
| @PrePersist | Executed before the entity manager persist operation is actually executed or cascaded. This call is synchronous with the persist operation. |
| @PreRemove | Executed before the entity manager remove operation is actually executed or cascaded. This call is synchronous with the remove operation. |
| @PostPersist | Executed after the entity manager persist operation is actually executed or cascaded. This call is invoked after the database INSERT is executed. |
| @PostRemove | Executed after the entity manager remove operation is actually executed or cascaded. This call is synchronous with the remove operation. |
| @PreUpdate | Executed before the database UPDATE operation. |
| @PostUpdate | Executed after the database UPDATE operation. |
| @PostLoad | Executed after an entity has been loaded into the current persistence context or an entity has been refreshed. |
Example
@Entity
@EntityListeners(class=Audit.class)
public class Cat {
@Id private Integer id;
private String name;
private Calendar dateOfBirth;
@Transient private int age;
private Date lastUpdate;
//getters and setters
/**
* Set my transient property at load time based on a calculation,
* note that a native Hibernate formula mapping is better for this purpose.
*/
@PostLoad
public void calculateAge() {
Calendar birth = new GregorianCalendar();
birth.setTime(dateOfBirth);
Calendar now = new GregorianCalendar();
now.setTime( new Date() );
int adjust = 0;
if ( now.get(Calendar.DAY_OF_YEAR) - birth.get(Calendar.DAY_OF_YEAR) < 0) {
adjust = -1;
}
age = now.get(Calendar.YEAR) - birth.get(Calendar.YEAR) + adjust;
}
}
public class LastUpdateListener {
/**
* automatic property set before any database persistence
*/
@PreUpdate
@PrePersist
public void setLastUpdate(Cat o) {
o.setLastUpdate( new Date() );
}
}
Source
