A java object within a hibernate application can be in one of the three states:

1. New/transient

2. Attached/persistent

3. Detached

Important points about object states in Hibernate

• When an object is created, it will be in the new/transient state.

  • Hibernate will not save any updates to the transient objects.

CRUD operations are Create(save), Read(select), Update(update) and Delete(delete).

Examples discussed here need to be tried out on top of the lab done @  http://javajee.com/lab-your-first-hibernate-43-program.

Session

Select, Save, update and delete operations in hibernate should be called within a session:

 SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();

You have different logging options in Hibernate and let us see some of those options quickly. Hibernate supports simple property based log enabling to supporting standard logging frameworks and even programmatically accessing log statistics.

First, you can enable showsql property in Hibernate to see the exact query being executed. You can set the property to true in the hibernate.cfg.xml XML configuration file. Please refer to http://javajee.com/lab-your-first-hibernate-43-program.

In JPA, the EntityManager controls the lifecycle of the entities.

Different ORM vendors provide its own entity manager, which is usually a wrapper around the core API and thus supports the JPA programming interfaces, life cycles and query language.

You obtain the EntityManager from an entity manager factory. EntityManagerFactory has the same role as SessionFactory in Hibernate.

Before working with hibernate in your code, you will need to configure Hibernate with information regarding your database such as host, port, credentials etc. You also need to create mappings that tell hibernate how to map the state of a Java entity to the columns of its corresponding table.

We can configure various hibernate features either through annotations or through xml files (hbm files). Preferred approach currently is annotations.

You can configure Hibernate mainly in three ways: