DAO Level and Services in Spring: Session Management

Question

Do I understand the principles of connecting DAO and the level of service? DAO performs the removal of basic objects, for example, id from db.

The service layer USES a DAO object and can call MORE THAN ONE DAO METHOD in a single function. So, the level of service should:

• create an instance of the DAO implementation object

• call as many DAO methods as possible

If a Dao implements an interface, should the DAO interface have a method setSessionFactory()?

As declaratively noted in Spring:

• DAO Object

• Service level methods and class in general

so that he gives what is needed?

Answer 1

, setSessionFactory(), DAO. DAO Spring, SessionFactory DAO.

Hibernate SessionFactory.getCurrentSession(), , SessionFactory DAO , Session .

, :

@Transactional
public void doSomething(){
    dao1.makeCall();
    dao2.makeOtherCall();
}

SessionFactory, DAO , Session. .

Answer 2

, , , setSessionFactory(), DAO. Hibernate DAO-, DAO Hibernate.

- (, ORM - ) ( DAO) .

setSessionFactory DAO-, , DAO, , Hibernate. , , .

Answer 3

• spring ( ).
• DAO sessionFactory.getCurrentSession() tp
• there is SessionFactoryintroduced in the DAO.
• have a DAO in the field singleton
• use declarative transactions (either with <aopor with @Transactional)
• DAO is injected into service objects through regular dependency injection. Similarly, service classes are introduced where they are needed.