Meta-annotation used to mark another annotation as providing configuration for a customidentifier generator. This is the best way to work with customized identifier generation in Hibernate.

For example, if we have a custom identifier generator:

 public class CustomSequenceGenerator implements BeforeExecutionGenerator {     public CustomSequenceGenerator(CustomSequence config, Member annotatedMember,                                    GeneratorCreationContext context) {         ...     }     ... }

Then we may also define an annotation which associates this generator with an entity and supplies configuration parameters:

 @IdGeneratorType(CustomSequenceGenerator.class) @Retention(RUNTIME) @Target({METHOD,FIELD}) public @interface CustomSequence {     String name();     int startWith() default 1;     int incrementBy() default 50; }

and we may use it as follows:

 @Id @CustomSequence(name = "mysequence", startWith = 0) private Integer id;

We did not use the JPA-definedGeneratedValue here, since that API is designed around the use of stringly-typed names. The@CustomSequence annotation itself implies thatid is a generated value.

An id generator annotation may have members, which are used to configure the id generator, if either:

• the id generator implementsAnnotationBasedGenerator, or
• the id generator class has a constructor with the same signature asAnnotationBasedGenerator.initialize(A, java.lang.reflect.Member, org.hibernate.generator.GeneratorCreationContext).

For a more complete example, see the annotationUuidGenerator and the corresponding generator classUuidGenerator.

A@IdGeneratorType annotation must have retention policyRetentionPolicy.RUNTIME.

If aGenerator may be used to generate values of non-identifier fields, its generator annotation should also be meta-annotated@ValueGenerationType.