An entity is a type on its own and has an existence of its own (e.g. Course, User etc.).

A value type is a type which doesn't have existence of its own, but belongs to an entity (e.g. Address of an User). Value types are always completely owned by their containing entity.

Defining entities and value types in Hibernate

@Entity annotation (javax.persistence.Entity) over the class tell hibernate to treat this class as our entity class that needs to be saved. [node:read-more:link]

Here we will discuss most commonly used basic annotations in hibernate - @Entity, @Table, @Id, @GeneratedValue, @Column, @Basic, @Transient, @Temporal and @Lob. Even though many annotations has both JPA (java.persistance) and hibernate (org.hibernate) versions, it is preferred to use JPA annotations whenever possible. As you can see below, some of the hibernate specific annotations are already deprecated.

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 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. [node:read-more:link]