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Spring Annotation Programming Model
This document is being introduced in conjunction with the release of Spring Framework 4.2; however, this document is still a work in progress. As such, you can expect to see multiple updates throughout the course of the 4.2.x timeline.
Over the years, the Spring Framework has continually evolved its support for annotations, meta-annotations, and composed annotations. This document is intended to aid developers (both end users of Spring and developers of the Spring Framework and Spring portfolio projects) in the development and use of annotations with Spring.
This document has the following primary goals.
- Explain how to use annotations with Spring.
- Explain how to develop annotations for use with Spring.
- Explain how Spring finds annotations (i.e., how Spring's annotation search algorithms work).
This document does not aim to explain the semantics or configuration options for particular annotations in the Spring Framework. For details on a particular annotation, developers are encouraged to consult the corresponding Javadoc of applicable sections of the reference manual.
Spring Framework 4.2 introduces first-class support for declaring and
looking up aliases for annotation attributes. The new @AliasFor
annotation can be used to declare a pair of aliased attributes within
a single annotation or to declare an alias from one attribute in a
custom composed annotation to an attribute in a meta-annotation.
For example, @ContextConfiguration from the spring-test module
is now declared as follows:
public @interface ContextConfiguration {
@AliasFor("locations")
String[] value() default {};
@AliasFor("value")
String[] locations() default {};
// ...
}
Similarly, composed annotations that override attributes from
meta-annotations can now use @AliasFor for fine-grained control
over exactly which attributes are overridden within an annotation
hierarchy. In fact, it is now possible to declare an alias for the
value attribute of a meta-annotation.
For example, one can now develop a composed annotation with a custom attribute override as follows.
@ContextConfiguration
public @interface MyTestConfig {
@AliasFor(annotation = ContextConfiguration.class, attribute = "value")
String[] xmlFiles();
// ...
}
org.springframework.cache.annotation.Cacheableorg.springframework.cache.annotation.CacheEvictorg.springframework.cache.annotation.CachePutorg.springframework.context.annotation.ComponentScan.Filterorg.springframework.context.annotation.ComponentScanorg.springframework.context.annotation.ImportResourceorg.springframework.context.annotation.Scopeorg.springframework.context.event.EventListenerorg.springframework.jmx.export.annotation.ManagedResourceorg.springframework.messaging.handler.annotation.Headerorg.springframework.messaging.handler.annotation.Payloadorg.springframework.messaging.simp.annotation.SendToUserorg.springframework.test.context.ActiveProfilesorg.springframework.test.context.ContextConfigurationorg.springframework.test.context.jdbc.Sqlorg.springframework.test.context.TestExecutionListenersorg.springframework.test.context.TestPropertySourceorg.springframework.transaction.annotation.Transactionalorg.springframework.transaction.event.TransactionalEventListenerorg.springframework.web.bind.annotation.ControllerAdviceorg.springframework.web.bind.annotation.CookieValueorg.springframework.web.bind.annotation.CrossOriginorg.springframework.web.bind.annotation.MatrixVariableorg.springframework.web.bind.annotation.RequestHeaderorg.springframework.web.bind.annotation.RequestMappingorg.springframework.web.bind.annotation.RequestParamorg.springframework.web.bind.annotation.RequestPartorg.springframework.web.bind.annotation.ResponseStatusorg.springframework.web.bind.annotation.SessionAttributesorg.springframework.web.portlet.bind.annotation.ActionMappingorg.springframework.web.portlet.bind.annotation.RenderMapping