What's the difference between @Component, @Repository & @Service annotations in Spring?

Question

Can @Component, @Repository and @Service annotations be used interchangeably in Spring or do they provide any particular functionality besides acting as a notation device?

Answer 1

Spring provides four different types of auto component scan annotations, they are @Component, @Service, @Repository and @Controller. Technically, there is no difference between them, but every auto component scan annotation should be used for a special purpose and within the defined layer.

@Component: It is a basic auto component scan annotation, it indicates annotated class is an auto scan component.

@Controller: Annotated class indicates that it is a controller component, and mainly used at the presentation layer.

@Service: It indicates annotated class is a Service component in the business layer.

@Repository: You need to use this annotation within the persistence layer, this acts like database repository.

One should choose a more specialised form of @Component while annotating their class as this annotation may contain specific behavior going forward.