3. Tutorial Using Native Hibernate APIs and Annotation Mappings

Objectives

• Bootstrap a Hibernate SessionFactory

• Use annotations to provide mapping information

• Use the Hibernate native APIs

3.1. The Hibernate configuration file

The contents are identical to The Hibernate configuration file with one important difference…​ The <mapping/> element at the very end naming the annotated entity class using the class attribute.

3.2. The annotated entity Java class

The entity class in this tutorial is org.hibernate.tutorial.annotations.Event which follows JavaBean conventions. In fact the class itself is identical to the one in The entity Java class, except that annotations are used to provide the metadata, rather than a separate mapping file.

Example 7. Identifying the class as an entity

@Entity
@Table( name = "EVENTS" )
public class Event {
    ...
}

The @javax.persistence.Entity annotation is used to mark a class as an entity. It functions the same as the <class/> mapping element discussed in The mapping file. Additionally the @javax.persistence.Table annotation explicitly specifies the table name. Without this specification, the default table name would be EVENT.

Example 8. Identifying the identifier property

@Id
@GeneratedValue(generator="increment")
@GenericGenerator(name="increment", strategy = "increment")
public Long getId() {
    return id;
}

@javax.persistence.Id marks the property which defines the entity’s identifier.

@javax.persistence.GeneratedValue and @org.hibernate.annotations.GenericGenerator work in tandem to indicate that Hibernate should use Hibernate’s increment generation strategy for this entity’s identifier values.

Example 9. Identifying basic properties

public String getTitle() {
    return title;
}
@Temporal(TemporalType.TIMESTAMP)
@Column(name = "EVENT_DATE")
public Date getDate() {
    return date;
}

As in The mapping file, the date property needs special handling to account for its special naming and its SQL type.

Attributes of an entity are considered persistent by default when mapping with annotations, which is why we don’t see any mapping information associated with title.

3.3. Example code

org.hibernate.tutorial.annotations.AnnotationsIllustrationTest is essentially the same as org.hibernate.tutorial.hbm.NativeApiIllustrationTest discussed in Example code.

3.4. Take it further!

Practice Exercises

• Add an association to the Event entity to model a message thread. Use the User Guide for more details.

• Add a callback to receive notifications when an Event is created, updated or deleted. Try the same with an event listener. Use the User Guide for more details.