Hibernate ORM 5.3 implements the JPA 2.2 standard. Over the following weeks, we are going to present various features introduced by JPA 2.2.
If Hibernate ORM 5.2 has added support for repeating Hibernate-specific annotations, JPA 2.2 will allow you to do the same with the JPA-specific annotations.
In this article, we are going to see how the repeating annotations feature is going to simplify your entity mappings.
Prior to JPA 2.2
Now, before JPA 2.2, if you wanted to use multiple @NamedQuery annotations,
you had to use @NamedQueries as well.
@NamedQueries({
@NamedQuery(
name = "get_person_by_name",
query = "select p from Person p where name = :name"
),
@NamedQuery(
name = "get_read_only_person_by_name",
query = "select p from Person p where name = :name",
hints = {
@QueryHint(
name = "org.hibernate.readOnly",
value = "true"
)
}
)
})
@Entity
public class Person {
...
}JPA 2.2
JPA 2.2 adds support for repeating annotations feature introduced in Java 8.
If you open the JPA 2.2, @NamedQuery annotation, the source code looks as follows:
@Repeatable(NamedQueries.class)
@Target({TYPE})
@Retention(RUNTIME)
public @interface NamedQuery {
/**
* (Required) The name used to refer to the query with the {@link EntityManager}
* methods that create query objects.
*/
String name();
/** (Required)
* The query string in the Java Persistence query language.
*/
String query();
/**
* (Optional) The lock mode type to use in query execution. If a <code>lockMode</code>
* other than <code>LockModeType.NONE</code> is specified, the query must be executed in
* a transaction and the persistence context joined to the transaction.
* @since Java Persistence 2.0
*/
LockModeType lockMode() default NONE;
/** (Optional) Query properties and hints. May include
* vendor-specific query hints.
*/
QueryHint[] hints() default {};
}Notice the first line, @Repeatable(NamedQueries.class), which tells that the @NamedQueries annotation is to be used
when we repeat the @NamedQuery multiple times.
So, behind the scenes, even if won’t declare the @NamedQueries annotation, Java will still use it.
Now, using the repeating annotation support, we can change the Person entity mapping as follows:
@NamedQuery(
name = "get_person_by_name",
query = "select p from Person p where name = :name"
)
@NamedQuery(
name = "get_read_only_person_by_name",
query = "select p from Person p where name = :name",
hints = {
@QueryHint(
name = "org.hibernate.readOnly",
value = "true"
)
}
)
@Entity
public class PersonRepeatingAnnotation {
...
}Much better, right?
