Can @Component
, @Repository
and @Service
annotations be used interchangeably in Spring or do they provide any particular functionality besides acting as a notation device?
In other words, if I have a Service class and I change the annotation from @Service
to @Component
, will it still behave the same way?
Or does the annotation also influence the behavior and functionality of the class?
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.
@Service annotation is used with classes that provide some business functionalities. @Repository Annotation is used to indicate that the class provides the mechanism for storage, retrieval, update, delete and search operation on objects. @Service Annotation is a specialization of @Component Annotation.
@Component is a class-level annotation, but @Bean is at the method level, so @Component is only an option when a class's source code is editable. @Bean can always be used, but it's more verbose. @Component is compatible with Spring's auto-detection, but @Bean requires manual class instantiation.
Spring @Repository annotation is used to indicate that the class provides the mechanism for storage, retrieval, search, update and delete operation on objects.
From Spring Documentation:
The
@Repository
annotation is a marker for any class that fulfils the role or stereotype of a repository (also known as Data Access Object or DAO). Among the uses of this marker is the automatic translation of exceptions, as described in Exception Translation.Spring provides further stereotype annotations:
@Component
,@Service
, and@Controller
.@Component
is a generic stereotype for any Spring-managed component.@Repository
,@Service
, and@Controller
are specializations of@Component
for more specific use cases (in the persistence, service, and presentation layers, respectively). Therefore, you can annotate your component classes with@Component
, but, by annotating them with@Repository
,@Service
, or@Controller
instead, your classes are more properly suited for processing by tools or associating with aspects.For example, these stereotype annotations make ideal targets for pointcuts.
@Repository
,@Service
, and@Controller
can also carry additional semantics in future releases of the Spring Framework. Thus, if you are choosing between using@Component
or@Service
for your service layer,@Service
is clearly the better choice. Similarly, as stated earlier,@Repository
is already supported as a marker for automatic exception translation in your persistence layer.
Annotation | Meaning |
---|---|
@Component | generic stereotype for any Spring-managed component |
@Repository | stereotype for persistence layer |
@Service | stereotype for service layer |
@Controller | stereotype for presentation layer (spring-mvc) |
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