Can I have Hibernate create an object through factory method?

Question

Is there a way to map a factory method in Hibernate (as opposed to having Hibernate call a default constructor and reflectively set properties or fields)?

And if it can't be mapped, does Hibernate provide a hook for custom object creation on a class by class basis?

Thanks!

Answer 1

This is doable using either:

• a custom EntityPersister implementation (that you can register for a particular entity during Hibernate initialization using a custom Configuration) ~or~
• a custom Interceptor implementing the Interceptor.instantiate() method

I think the Interceptor approach is easier. Here is the javadoc of the Interceptor.instantiate():

/**
 * Instantiate the entity class. Return <tt>null</tt> to indicate that Hibernate should use
 * the default constructor of the class. The identifier property of the returned instance
 * should be initialized with the given identifier.
 *
 * @param entityName the name of the entity
 * @param entityMode The type of entity instance to be returned.
 * @param id the identifier of the new instance
 * @return an instance of the class, or <tt>null</tt> to choose default behaviour
 */
public Object instantiate(String entityName, EntityMode entityMode, Serializable id) throws CallbackException;

Answer 2

Take a look at UserType. You'd need to call your factory in nullSafeGet() and populate all the fields yourself though. Reverse work is done in nullSafeSet().