Hibernate SessionFactory is the factory class through which we get sessions and perform database operations.
Hibernate SessionFactory provides three methods through which we can get Session object - getCurrentSession()
, openSession()
and openStatelessSession()
.
Hibernate SessionFactory
getCurrentSession() method returns the session bound to the context. But for this to work, we need to configure it in hibernate configuration file like below.
<property name="hibernate.current_session_context_class">thread</property>
If its not configured to thread, then we will get below exception.
Exception in thread "main" org.hibernate.HibernateException: No CurrentSessionContext configured!
at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:1012)
at com.journaldev.hibernate.main.HibernateSessionExample.main(HibernateSessionExample.java:16)
Since this session object belongs to the hibernate context, we don’t need to close it. Once the session factory is closed, this session object gets closed. Hibernate Session objects are not thread safe, so we should not use it in multi-threaded environment. We can use it in single threaded environment because it’s relatively faster than opening a new session.
Hibernate SessionFactory
openSession() method always opens a new session. We should close this session object once we are done with all the database operations. We should open a new session for each request in multi-threaded environment. For web application frameworks, we can choose to open a new session for each request or for each session based on the requirement.
Hibernate SessionFactory
openStatelessSession() method returns instance of StatelessSession
. There is another overloaded method where we can pass java.sql.Connection
object to get a stateless session object from hibernate. StatelessSession in Hibernate does not implement first-level cache and it doesn’t interact with any second-level cache. Since it’s stateless, it doesn’t implement transactional write-behind or automatic dirty checking or do cascading operations to associated entities. Collections are also ignored by a stateless session. Operations performed via a stateless session bypass Hibernate’s event model and interceptors. It’s more like a normal JDBC connection and doesn’t provide any benefits that come from using hibernate framework. However, stateless session can be a good fit in certain situations. For example where we are loading bulk data into database and we don’t want hibernate session to hold huge data in first-level cache memory. A simple program showing Hibernate SessionFactory methods usage is given below.
package com.journaldev.hibernate.main;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.StatelessSession;
import com.journaldev.hibernate.util.HibernateUtil;
public class HibernateSessionExample {
public static void main(String[] args) {
SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
//Current Session - no need to close
Session currentSession = sessionFactory.getCurrentSession();
//open new session
Session newSession = sessionFactory.openSession();
//perform db operations
//close session
newSession.close();
//open stateless session
StatelessSession statelessSession = sessionFactory.openStatelessSession();
//perform stateless db operations
//close session
statelessSession.close();
//close session factory
sessionFactory.close();
}
}
That’s all for SessionFactory in Hibernate and it’s different methods to obtain session object.
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Hi Pankaj, Your explanation put me into curiosity that how in multithreading, getCurrentSeasson method will create problem . can anyone explain? I do some research but could not find any relevand blog for that
- Amit Sarkar
Hi i’m getting deleted data in my service response can you help me what can be the solution for that.and also some time alternate time data is coming and not coming.
- Sabndeep Kumar Prasad
Hi Pankaj, When I am using sessionFactory.getCurrentSession() and create criteria query, Its give me error has “createCriteria is not valid without active transaction”
- farhan
Using getCurrentSession(), we cannot perform lazy loading whereas openSession supports lazy loading
- Vishwas
Hi Pankaj, What I interpret from article that hibernate CurrentSession() is not thread safe only and rest two OpenSession() and OpenStatelessSession() are thread safe. Can you please confirm?
- manish gupta
Hi pankaj, You have really explained the concepts very well.It was really helpful going through this website.If you can avoid more technical and use simple words it will be still easier to understand the concepts.Thanks a lot for sharing your knowledge.
- nagesh