Hibernate and Spring - Beginning Hibernate: From Novice to Professional - page 304

public interface PaperDao {
public List<Paper> getAll();
public void createPaper(final Paper paper);
public Paper getPaper(final Integer paperId);
public Paper createArticle(final Integer paperId,final Article article);
}
Ideally, you should define an interface to specify the methods that your DAO will con-
tain. Our sample application requires a single DAO with a few simple methods (shown in
Listing C-7).
With the interface clearly specified, your DAO class should then extend the
HibernateDaoSupport class and implement the interface that you have defined. Extending
HibernateDaoSupport provides a number of get/set pairs for necessary Spring attributes
(specifically the sessionFactory attribute) and various helper methods for implementing
your DAO. A typical DAO method implementation using these methods is shown in
Listing C-8.
Listing C-8. Implementing getAll() Using the Methods from the HibernateDaoSupport Class
@SuppressWarnings("unchecked")
public List<Paper> getAll() {
Session session = getSession();
List<Paper> papers = (List<Paper>)session.createQuery("from Paper").list();
releaseSession(session);
return papers;
}
The getSession() and releaseSession() methods are derived from the DAO class. They
are roughly equivalent to the session factory's openSession() method and the session's close()
method, respectively.
The HibernateDaoSupport class also provides access to an appropriately configured helper
object: HibernateTemplate . Using this object, the preceding code can be rewritten as shown in
Listing C-9.
Listing C-9 Implementing the getAll() Method Using the HibernateTemplate Class
@SuppressWarnings("unchecked")
public List<Paper> getAll() {
return (List<Paper>)getHibernateTemplate().find("from Paper");
}
This notably reduces the amount of boilerplate session management code that is
required to process this simply query. HibernateTemplate provides a set of methods
(shown in Table C-1) that allow you to carry out most of the basic Hibernate operations
in a similar single line of code.