Java 1.5 required
Annotations are supported in Java 1.5 and later. If you are using 1.4 you can use XDoclet to help generate your mapping files.
Basic column mapping
unique column restraint
To specifiy an unique key constraint on a column use
@Column(unique=true)
Enumerations
Enums are saved as either text or ordinals depending on the underlying column.
Ignored or transient fields
To prevent persistence of a field, annotate it with @Transient so it will not be mapped by hibernate.
Cascade all-delete-orphan
The standard EJB annotations do not have the delete orphan option.
@OneToMany {cascade=CascadeType.ALL}
The above is from the javax.persistence package.
Instead, we can use the original Hibernate mapping attributes this way:
@org.hibernate.annotations.Cascade(
{org.hibernate.annotations.CascadeType.ALL,org.hibernate.annotations.CascadeType.DELETE_ORPHAN}
)