JDK 5.0 introduced XDoclet-style annotations at the language level, type-safe and checked at compile time. This mechnism is more powerful than XDoclet annotations and better supported by tools and IDEs. IntelliJ IDEA, for example, supports auto-completion and syntax highlighting of JDK 5.0 annotations. The new revision of the EJB specification (JSR-220) uses JDK 5.0 annotations as the primary metadata mechanism for entity beans. Hibernate3 implements the EntityManager of JSR-220 (the persistence API), support for mapping metadata is available via the Hibernate Annotations package, as a separate download. Both EJB3 (JSR-220) and Hibernate3 metadata is supported.

This is an example of a POJO class annotated as an EJB entity bean:

@Entity(access = AccessType.FIELD)
public class Customer implements Serializable {

    @Id;
    Long id;

    String firstName;
    String lastName;
    Date birthday;

    @Transient
    Integer age;

    @Embedded
    private Address homeAddress;

    @OneToMany(cascade=CascadeType.ALL)
    @JoinColumn(name="CUSTOMER_ID")
    Set<Order> orders;

    // Getter/setter and business methods
}

Note that support for JDK 5.0 Annotations (and JSR-220) is still work in progress and not completed. Please refer to the Hibernate Annotations module for more details.