session help

[Andy Hahn]

I have read the book Pro Hibernate 3, and may have gained some confusion in the process My questions is do I always have to close a session when I am done with it? I would think I would but the authors of the book do not do this in their code examples. For example, the authors use the following hibnernate helper class below but do not ever close the session when using this helper class:

    
import org.hibernate.*;
import org.hibernate.cfg.Configuration;
import org.apache.log4j.Logger;
 
import java.util.List;
 
public class HibernateHelper {
    private static final Logger LOG = Logger.getLogger(HibernateHelper.class);
    private static final ThreadLocal session = new ThreadLocal();
    private static final SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
 
    private HibernateHelper() {
    }
 
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
 
    public static Session getSession() {
        Session session = (Session)HibernateHelper.session.get();
        if (session == null) {
            session = getSessionFactory().openSession();
            HibernateHelper.session.set(session);
        }
        return session;
    }
}
 

[Paul Sturrock]

My questions is do I always have to close a session when I am done with it?

By and large the answer to that is yes. Unless you are explicitly flushing the session it will become stale (i.e. the objects in it are not really representative of the data in your database) if you keep it open for a long time.

[Andy Hahn]

Thanks. Below is a closeSession() method in case anyone wants to use the code in this post:

   
//close a session
public static Session closeSession() {
   Session session = (Session)HibernateHelper.session.get();
   if (session != null) {
      session.close();
      HibernateHelper.session.set(null);
   }
   return session;
}