Something About Hibernate

Hibernate is an Object Relational Mapping solution for Java, and it’s an open-source persistent framework.

It is a powerful, High Performance, Object Relational Persistence Query Service for any Java Application.

How Hibernate Functions:-

  • Hibernate maps Java Classes to Database Types and Java Data types to SQL data types, and thus it makes the life of a programmer easier.
  • Hibernate make use of XML configurations for mapping Java Classes to  database Objects.
  • Provides simple API for accessing Java Objects to and from the database.
  • Changes in the database can be reflected by changing the XML configuration file.
  • It Abstracts the SQL queries & helps us working with Java Objects.
  • It doesn’t require an application server to work.
  •  Can manage complex associations through Objects.
  • Ease in Data Retrieval
  • And It supports almost all RDBMS.
  • It uses existing Java API’s like JDBC ,JNDI, Java TransactionAPI. JDBC provides a rudimentary level of abstraction,and also it allows any database with a JDBC driver can be integrated with Hibernate.
  • JNDI and Java Transaction API (JTI) helps Hibernate to get integrated with J2EE application servers.

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Hibernate sits between Traditional Java objects and database server to handle all the work in persisting objects based on appropriate Object-Relational mechanisms and patterns.

A High Level Hibernate Architecture

 hibernate_high_level

Objects which gave birth in an Hibernate Application

  • Configuration Object
  • Session Factory Object
  • Session Object
  • Transaction Object
  • Query Object
  • Criteria Object

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  • Configuration Object

It’ the first ever object that get created in an Hibernate Application, and it’s created automatically during application initialization process. The two key components of Configuration Objects are :

  1. Database Connection => which is handled by hibernate.properties and hibernate.cfg.xml.
  2. Class Mapping Setup => This helps in creating in connection with Java Classes and DB tables.
  •  Session Factory Object

The above mentioned Configuration Object is used to create Session Factory Object which inturn configures Hibernate for the application with the supplied configuration file => which instantiates a Session Object. Session Factory Object is created during application startup.We will need one SessionFactory Object per Database and vice versa.

  • Session Object

The basic purpose of this object is to get a physical connection with the database & this object will be instantiated each time when database interaction occurs. They are not thread safe( should be destroyed/created as needed).

  • Transaction Object

This is an optional object , and Hibernate applications may choose not to use this interface.

  •   Query Object

Query Objects use SQL or Hibernate Query Language string to retrieve data from the database and create objects.

  • Criteria Object

These objects are used to create and execute object oriented criteria queries to retrieve objects.


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