Hibernate config

In this section, you will learn about Hibernate config or configuration in Hibernate.

Hibernate config

Hibernate config

In this section, you will learn about Hibernate config or configuration in Hibernate.

The configuration of Hibernate is handled by the instance of org.hibernate.cfg.Configuration . It symbolizes the complete mapping between Java data types to the SQL database or database table. It is used to construct org.hibernate.SessionFactory . Various XML mapping files or Java Annotations compilation build these mapping.

Following 3 types of configuration is provided by the Hibernate :

(1) hibernate.cfg.xml

To define a Hibernate Configuration info a resource file named hibernate.cfg.xml is used. Using this configuration file various of information is provided to the Hibernate such as :

  • connection.driver_class : This property element is used to provide the name of the driver class.
  • connection.url : This property element is used to provide the url for the database connection.
  • connection.username : This property element is used to provide the username by which you are logging to the database.
  • connection.password : This property element is used to provide the password by which you are logging to the databse.
  • connection.pool_size : This property element configures the number of connections of connection pool of the built-in Hibernate.
  • dialect : This property defines the particular SQL variant with which the Hibernate will carry on a conversation. Use of this property is necessary when there are multiple databases are targeted by an application.

At last of you will be required to map the persistent class(POJO) file to the configuration.A simple configuration file hibernate.cfg.xml can be written as :

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"

<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://</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>

<mapping class="worker.Worker" />


(2) hibernate.properties

This property file contains the key-value pair for different hibernate configuration.

The sample hibernate.properties file is given below :

hibernate.connection.url= jdbc:mysql://
hibernate.transaction.factory_class = \
hibernate.transaction.manager_lookup_class = \
hibernate.dialect = org.hibernate.dialect.MySQLDialect

(3) Programmatic configuration

This is the manual configuration which needs to be done in Java file. We can get an instance of org.hibernate.cfg.Configuration directly by specifying mapped class using  .addClass( ).

Configuration cfg = new Configuration()

Building a SessionFactory

After creating instance of org.hibernate.cfg.Configuration , you can create instance of SessionFactory as follows:

SessionFactory sessions = cfg.buildSessionFactory();

Creating Session instance

 Between database table and application, Session represents a communication channel. From SessionFactory , Session can be created as follows:

Session session = sessions.openSession();