Hibernate

Hibernate is a Java framework that provides OR mapping functionality to define how Java objects are stored, modified, deleted, and retrieved.

The Hibernate architecture has 3 main components:

• connection management
• transaction management
• object-relational mapping

Hibernate uses POJO classes and XML mapping files to map to database tables.

The Hibernate Session is the main runtime interface between a Java application and Hibernate. SessionFactory allows the application to create a Hibernate Session by reading the configuration from hibernate.cfg.xml.

Important elements of the Hibernate mapping file include the following:

• <hibernate-mapping> root element
• <class> maps classes to DB entities
• <id> maps to the primary key of a table
• <generator> is used to generate the primary key for a new record. Values include increment, sequence, and assigned
• <property> maps attributes to columns

HQL is based on the relational object models and makes SQL object-oriented. It uses classes and proeprties instead of tables and columns. It supports polymorphism, associations, etc. and returns results as objects. It is also database independent.

Hibernate also supports native SQL statements.