Hibernate SessionFactory
In this tutorial we will learn about how the SessionFactory creates the session.
SessionFactory is an interface that extends the Referenceable and Serializable interfaces and produces the Session instances. In an application the SessionFactory instance is globally created and is thread safe that the Session instance can be obtained from this factory on receiving request from the client. Once the SessionFactory is created it can't be change, its internal state becomes set. Internal state of SessionFactory contains all of the metadata about ORM.
Syntax :
public interface SessionFactory extends Referenceable, Serializable
This interface also declares methods. Some of the useful methods are as follows :
- Session openSession() : This method is used to open
Session.
Syntax : Session openSession() throws HibernateException
Note : This method is overloaded in this interface with different signatures.
- StatelessSession openStatelessSession() : This method is
used to open a stateless Session.
Syntax : StatelessSession openStatelessSession()
- StatelessSession openStatelessSession(Connection connection) :
This method is used to open a stateless Session using the given JDBC Connection.
Syntax : StatelessSession openStatelessSession(Connection connection)
- boolean isClosed() : This method is used to check whether
the SessionFactory is closed or not.
Syntax : boolean isClosed()
- Session getCurrentSession() : This method is used to get
the current Session.
Syntax : Session getCurrentSession() throws HibernateException
Example
Here I am giving a simple example which will demonstrate you about how to use the SessionFactory in the application. This example will explain you how you can open a Session using SessionFactory. In this example we will use the Eclipse IDE for writing and compiling the application and MySQL for database connectivity. Here I have created a Java project in Eclipse then I have created different packages inside the src folder and then created classes inside the packages. I have created the hibernate XML mapping file inside the src folder where I have mapped the Class and its property with the table and its field. Then I have created a hibernate configuration file where I have provide the RDBMS informations inside the <property> sub tag of <session-factory> tag.
Person.java
package net.roseindia;
public class Person
{
int id;
String name;
public Person()
{
}
public Person(int id, String name) {
super();
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
PersonDetail.java
package net.roseindia;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class PersonDetail
{
private static SessionFactory sessionFactory;
private static ServiceRegistry serviceRegistry;
public static void main(String[] args)
{
Session session = null;
try
{
try
{
Configuration cfg = new Configuration().addResource(
"person.hbm.xml").configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(
cfg.getProperties()).buildServiceRegistry();
sessionFactory = cfg.buildSessionFactory(serviceRegistry);
}
catch (Throwable ex)
{
System.err.println("Failed to create sessionFactory object."+ ex);
throw new ExceptionInInitializerError(ex);
}
session = sessionFactory.openSession();
Transaction tx = session.beginTransaction();
Person person = (Person)session.get(Person.class, new Integer(1));
System.out.println("person.getName()=======>"+person.getName());
person.setName("Roseindia");
tx.commit();
session.flush();
System.out.println("Done");
} catch (Exception e) {
System.out.println(e.getMessage());
} finally {
session.close();
}
}
}
Person.hbm.xml
<?xml version='1.0'?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="net.roseindia"> <class name="Person" table="person1"> <id name="id" type="int" column="Id" > <generator class="assigned"/> </id> <property name="name"> <column name="Name" /> </property> </class> </hibernate-mapping>
hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory> <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/record </property> <property name="hibernate.connection.username">root</property> <property name="hibernate.connection.password">root</property> <property name="hibernate.connection.pool_size">10</property> <property name="show_sql">true</property> <property name="dialect">org.hibernate.dialect.MySQLDialect</property> <property name="hibernate.current_session_context_class">thread</property> </session-factory> </hibernate-configuration>
