Spring Stereotype Annotations

 

The Spring framework provides you with some special annotations. These annotations are used to create Spring beans automatically in the application context. The stereotype annotations in spring are @Component, @Controller, @Service & @Repository.

The main stereotype annotation is @Component.

“Annotations denoting the roles of types or methods in the overall architecture (at the conceptual, rather than implementation, level)” from java docs.

 

There are some stereotype meta-annotations which is derived from @Component annotation.

Meta Annotation: - Generally in java, an annotation is termed as meta-annotation if it is used on another annotation.

 

@Controller: - Used to create spring beans at the Controller layer.

@Service: - Used to create spring bean at the Service Layer. We mark beans @Service to indicate that they are holding business logic. Besides being used in the service layer, there is not any special use for this annotation.

@Repository: - Used to create a spring bean at the Persistence Layer, which will act as a database repository at the DAO layer. Its job is to catch persistence-specific exceptions and re-throw them as one of the Spring’s unified unchecked exceptions.

To detect these beans automatically, spring uses classpath scanning annotations.

Then it registers each bean in the ApplicationContext.

The major difference between these stereotypes is that they are used for different classifications. When we annotate a class for auto detection, we should use the respective stereotype.

For more info read the Spring doc here.