Difference between Session and Sessionfactory Hibernate?

Difference between Session and sessionfactory in Hibernate?

Basically session will be created from the sessionfactory instances. I have listed down the few differences between the session and sessionfactory in hibernate.

Sessionfactory:

• It is one instance per datasource/database.
• It is thread safe.
• It is a heavy weight object, because it maintains datasources, mappings, hibernate configuration information’s etc.
• Sessionfactory will create and manage the sessions.
• If you have 5 datasources/databases, then you must create 5 session factory instances.
• sessionfactory is an immutable object and it will be created as singleton while the server initializes itself.

What is session factory & How to create a sessionfactory ?

Session:

• It is one instance per client/thread/one transaction.
• It is not thread safe.
• It is light weight.
• sessions will be opened using sessionfactory.openSession() and some database operations will be done finally session will be closed using session.close().

How Session will be created from session factory [sample snippet]?

// creating the session from the sessionfactory
Session session = HibernateConfig.getSessionFactory().openSession();
// fetching
session.beginTransaction();
Author authorFetch = (Author)session.get(Author.class, 2);
System.out.println(authorFetch.getAuthorName());
System.out.println(authorFetch.getSiteName());
session.getTransaction().commit();
// closing the session factory session
session.close();
HibernateConfig.getSessionFactory().close();

Full Executable program can be found here