How do you map Java Objects with Database tables?

Hibernate offers a query language that embodies a very powerful and flexible mechanism to query, store, update, and retrieve objects from a database. This language, the Hibernate Query Language (HQL), is an object-oriented extension to SQL.

What role does the Session interface play in Hibernate?

The Session interface is the primary interface used by Hibernate applications. It is a single-threaded, short-lived object representing a conversation between the application and the persistent store. It allows you to create Query objects to retrieve persistent objects.

Session session = sessionFactory.openSession();
Session interface role:
Wraps a JDBC connection
Factory for Transaction
Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier

What are the Core interfaces are of Hibernate framework?

The five core interfaces are used in just about every Hibernate application. Using these interfaces, you can store and retrieve persistent objects and control transactions.
Session interface
SessionFactory interface
Configuration interface
Transaction interface
Query and Criteria interfaces

What is Hibernate?

Hibernate is a open source pure Java object-relational mapping (ORM) and persistence framework that allows you to map plain old Java objects (POJO) to relational database tables using (XML) configuration files. Its purpose is to relieve the developer from a significant amount of relational data persistence-related programming tasks.

Why Hibernate?

Object Relational Mapping Tools have lot of advantages which will help an organizations increase the productivity and improve quality of applications developed.
The main advantage of ORM like hibernate is that it abstracts developers from writing SQL. Apart from this, ORM provides following benefits:
- Improved productivity
- High-level object-oriented API
- Less Java code to write
- No or less SQL to write
- Improved performance - Could be case to case basis, but a well designed application in Hibernate would definitely be having a good performance due to its optimization features like lazy loading, and caching.
- Sophisticated caching
- Lazy loading
- Eager loading
- Improved maintainability
- Improved portability
- ORM framework generates database-specific DML or DDL for you which can help you deploy applicaiton in different environments.

What Does Hibernate Simplify?

Hibernate framework can simplify following things:
- Writing/Updating and retrieving your domain objects
- Making database column and table name changes
- Centralizing pre save and post retrieve logic
- Complex joins for retrieving related items
- Schema creation from object model
- Cascaded features can help retrieve related objects in memory at one shot or could be loaded lazily if needed.

What is Hibernate xml mapping file?

Hibernate mapping file tells Hibernate which tables and columns to use to load and store objects.