@Component
@controller
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Controller {
/**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any
*/
String value() default "";
}
@Service
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Service {
/**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any
*/
String value() default "";
}
@Repository
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Repository {
/**
* The value may indicate a suggestion for a logical component name,
* to be turned into a Spring bean in case of an autodetected component.
* @return the suggested component name, if any
*/
String value() default "";
}
@Bean
@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Bean {
/**
* The name of this bean, or if plural, aliases for this bean. If left unspecified
* the name of the bean is the name of the annotated method. If specified, the method
* name is ignored.
*/
String[] name() default {};
/**
* Are dependencies to be injected via autowiring?
*/
Autowire autowire() default Autowire.NO;
/**
* The optional name of a method to call on the bean instance during initialization.
* Not commonly used, given that the method may be called programmatically directly
* within the body of a Bean-annotated method. Default value is {@code ""}, indicating
* that no init method should be called.
*/
String initMethod() default "";
/**
* The optional name of a method to call on the bean instance upon closing the
* application context, for example a {@code close()} method on a JDBC {@code
* DataSource} implementation, or a Hibernate {@code SessionFactory} object.
* The method must have no arguments but may throw any exception.
* <p>As a convenience to the user, the container will attempt to infer a destroy
* method against object returned from the {@code @Bean} method. For example, given a
* {@code @Bean} method returning an Apache Commons DBCP {@code BasicDataSource}, the
* container will notice the {@code close()} method available on that object and
* automatically register it as the {@code destroyMethod}. This 'destroy method
* inference' is currently limited to detecting only public, no-arg methods named
* 'close'. The method may be declared at any level of the inheritance hierarchy, and
* will be detected regardless of the return type of the {@code @Bean} method, i.e.
* detection occurs reflectively against the bean instance itself at creation time.
* <p>To disable destroy method inference for a particular {@code @Bean}, specify an
* empty string as the value, e.g. {@code @Bean(destroyMethod="")}.
* <p>Note: Only invoked on beans whose lifecycle is under the full control of the
* factory, which is always the case for singletons but not guaranteed
* for any other scope.
* @see org.springframework.context.ConfigurableApplicationContext#close()
*/
String destroyMethod() default AbstractBeanDefinition.INFER_METHOD;
}
@Component와 @Bean의 차이
- @Bean 어노테이션의 경우 개발자가 직접 제어가 불가능한 외부라이브러리 등을 Bean으로 만들때 사용한다.
- @Component는 개발자가 직접 작성한 class를 Bean으로 등록하기위해서 사용한다.
- @Service, @Controller, @Repository은 실제 동작하는건 같지만 기능별로 분류해 놓았다.
@Component Scan이란
<context:component-scan base-package="kr.co.styudy" />
- Spring에서는 XML에 위의 코드를 작성함으로써 @Component가 해당 패키지를 기본으로하여 어노테이션을 읽어 Bean으로 등록해주는 역할을 한다.
- 실제 스캐닝은 ConfigurationclassPostProcessor라는 BeanFactoryPostProcessor에 의해 처리가 된다.
- excludeFilters, includeFilters 등을 사용하게 되면 Bean으로 등록하지 못하게 한다.
평션을 사용한 빈 등록
public static void main(String[] args) {
new SpringApplicationBuilder()
.sources(Demospring51Application.class)
.initializers((ApplicationContextInitializer<GenericApplicationContext>)
applicationContext -> {
applicationContext.registerBean(MyBean.class); })
.run(args);
}