Stereotype and Meta Annotations in Spring

Spring Framework (24 Part Series)

1 Spring Configuration
2 External Properties in Spring
… 20 more parts…
3 Profiles in Spring
4 Spring Expression Language (SpEL)
5 How Spring implements Singleton Beans
6 Converting explicit into implicit configuration in Spring
7 Autowiring in Spring
8 Lazy Beans in Spring
9 @PostConstruct and @PreDestroy in Spring
10 Stereotype and Meta Annotations in Spring
11 Spring’s FactoryBean Interface
12 The Spring Bean Lifecycle
13 Spring AOP
14 Caching in Spring
15 Spring JDBC
16 Spring Transaction Management
17 JPA with Spring
18 JPA with Spring Boot
19 Spring Web MVC
20 Spring Boot for war
21 Spring MVC REST
22 Reactive Spring Applications
23 Spring Security
24 Spring Injection Types

@ComponentScan checks not only for components but for annotations that are themselves annotated with @Component too. Those are stereotype annotations:

• Component
• Controller
• Repository
• Service

We could add @Configuration and @RestController because @Configuration is annotated with @Component and @RestController is annotated with @Controller (some people disagree)

Meta-annotations are annotations that can be used to annotate other annotations. For example, the next custom annotation @MyTransactionalService is a meta-annotation:

@MyTransactionalService
public class TransferServiceImpl implements TransferService {
  ...
}

@Retention(RUNTIME)
@Target(TYPE)
@Service
@Transactional(timeout=60)
public @interface MyTransactionalService {
  String value() default "";
}

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原文链接：Stereotype and Meta Annotations in Spring