Package javax.decorator
Annotations relating to decorators.
A decorator implements one or more bean types and intercepts business method invocations of beans which implement those bean types. These bean types are called decorated types.
A decorator is a managed bean annotated @Decorator
.
Decorators are superficially similar to interceptors, but because they directly implement operations with business semantics, they are able to implement business logic and, conversely, unable to implement the cross-cutting concerns for which interceptors are optimized. Decorators are called after interceptors.
Decorated types
The set of decorated types of a decorator includes all
bean types of the managed bean that are Java interfaces,
except for Serializable
. The decorator bean
class and its superclasses are not decorated types of the
decorator. The decorator class may be abstract.
A decorator intercepts every method:
- declared by a decorated type of the decorator
- that is implemented by the bean class of the decorator.
A decorator may be an abstract class, and is not required to implement every method of every decorated type.
Delegate injection points
All decorators have a
delegate injection point.
A delegate injection point is an injection point of the bean
class annotated @Delegate
.
The type of the delegate injection point must implement or extend every decorated type. A decorator is not required to implement the type of the delegate injection point.
Enabled decorators
By default, a bean archive has no enabled decorators. A decorator must be explicitly enabled by listing its bean class under the <decorators> element of the beans.xml file of the bean archive. The order of the decorator declarations determines the decorator ordering. Decorators which occur earlier in the list are called first.
A decorator is bound to a bean if:
- The bean is eligible for injection to the delegate injection point of the decorator.
- The decorator is enabled in the bean archive of the bean.
If a managed bean class is declared final, it may not have decorators. If a managed bean has a non-static, non-private, final method, it may not have any decorator which implements that method.
A decorator instance is a dependent object of the object it decorates.
- See Also: