@Component、@Repository 和 @Repository 有什么区别?Spring中的@Service注释?
可以@Component, @Repository 和 @Service 注解在 Spring 中可以互换使用，或者它们是否提供除了作为注解设备之外的任何特定功能?
Can @Component, @Repository and @Service annotations be used interchangeably in Spring or do they provide any particular functionality besides acting as a notation device?
换句话说，如果我有一个 Service 类并且我将注解从 @Service 更改为 @Component，它的行为方式是否仍然相同?
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?
或者注解也会影响类的行为和功能?
Or does the annotation also influence the behavior and functionality of the class?
推荐答案
来自 Spring 文档:
@Repository 注释是任何满足存储库的角色或原型(也称为数据访问对象)或 DAO).该标记的用途之一是自动翻译例外，如 异常翻译.
The
@Repositoryannotation 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 提供了更多的原型注解:@Component、@Service、和 @Controller.@Component 是任何类型的通用构造型Spring 管理的组件.@Repository、@Service 和 @Controller 是@Component 的特化，用于更具体的用例(在分别是持久层、服务层和表示层).因此，您可以使用 @Component 注释您的组件类，但是，通过使用 @Repository、@Service 或 @Controller 注释它们相反，您的类更适合工具处理或与方面相关联.
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.
例如，这些原型注解为切入点制作理想的目标.@Repository、@Service 和@Controller 还可以在未来版本的春天框架.因此，如果您在使用@Component 或 @Service 为您的服务层，@Service 显然是更好的选择.同样，如前所述，@Repository 已经支持作为自动异常翻译的标记持久层.
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.
| 注释 | 意义 |
|---|---|
@Component | 任何 Spring 管理组件的通用构造型 |
@Repository | 持久层的原型 |
@Service | 服务层的原型 |
@Controller | 表示层的原型(spring-mvc) |
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