会话和会话工厂在休眠

Question

I am creating an application with Java, Hibernate and SQL Server. I have a doubt regarding the declaration of objects for Session and Session Factory. At first when I started to create the application I used to create session and session factory at all the times when needed. But now I notices that my application becomes slow when I create session and session factory as said above so I started creating all the needed sessions and session factories at my Log in page and specified the modifiers as public static.

    public static Session session = null;
    public static SessionFactory sessionfactory = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
    public static Session session1 = null;
    public static SessionFactory sessionfactory1 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
    public static Session session2 = null;
    public static SessionFactory sessionfactory2 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();

Now whenever I need the use the sessions and session factories I used to call the sessions as Login.session (loginpagefilename.sessionobject).

 Login.session = Login.sessionfactory.openSession();
        Login.session.beginTransaction();
        String hql = "FROM TEST_SERVICES_POJO lts WHERE NOT EXISTS (SELECT lsm.inttestid FROM PARAMETER_MAPPING_POJO lsm WHERE lsm.status = 1 and lsm.inttestid=lts.inttestid)";
        org.hibernate.Query query = Login.session.createQuery(hql);
        DefaultTableModel model = (DefaultTableModel) testtable.getModel();
        model.setRowCount(0);
        for (Iterator it = query.iterate(); it.hasNext();) {
            TEST_SERVICES_POJO slp = (TEST_SERVICES_POJO) it.next();
            Object[] row = {slp.getTestname()};
            model.addRow(row);
        }
        Login.session.getTransaction().commit();

Here in first I didn't used rollback feature of hibernate. But now I wish to implement rollback feature of hibernate. So following which method will give me better performance. Kindly suggest me a way. Thanks in advance.

Answer 1

The most important thing: never ever create more than one SessionFactory per application (unless you have more than one persistence-context, then create one per appplication and persistence-context). Keeping creating SessionFactories will first kill your performance and then your app-server due to OutOfMemoryError s. Create a SessionFactory at application startup and keep it around where it is accessible - store it in jndi, keep it in a global class or something like that.

Create Session s as needed - the best match often is one Session per transaction, so hibernate can utilise its caching-mechanism.