The detached object has the identification value of the database and can be transformed into a persistent object through methods such as update() and saveOrUpdate(). When the detached object is re-associated to the session, it becomes a persistent object again. When the session associated with a persistent object is closed, the persistent object becomes a detached object. There are records associated with it in the database. Persistent objects have the following characteristics:Ģ. Under the management of HIbernate persistence layer.
Although the object has a database identification value, it is no longer there. At this time, the persistent object becomes a detached object. When a session executes close() or clear(), evict(), the persistent object becomes a detached object. Because the corresponding data in the database has been deleted, the object is no longer associated with the database record. If you use hibernate's delete() method, the corresponding persistent object becomes a transient object. The object in this state has a corresponding record in the database and has a persistent identifier. In Hibernate, the transient object can be associated with the database through the save() or saveOrUpdate() method of the session The corresponding data is inserted into the database, and the instantaneous object is transformed into a persistent object. It is a carrier of information and does not have any relationship with the data of the database. The transient object exists in isolation in the memory. If there is no variable to reference the object, it will be recycled by the java virtual machine. Java objects that open up memory space by the new command.
Objects in a persistent state are also called PO (Persistence Object), transient objects and detached objects are also called VO (Value Object). Hibernate objects have three states, namely:
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