java 注入 原理_Spring Boot自动注入原理
启用自动注入
使用注解@EnableAutoConfiguration开启自动注入功能。
@EnableAutoConfiguration
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
// ignore...
}
@AutoConfigurationPackage
@Import(AutoConfigurationPackages.Registrar.class)
public @interface AutoConfigurationPackage {
}
Spring Boot通过AutoConfigurationImportSelector.class和AutoConfigurationPackages.Registrar.class这两个类配合使用，实现动态注入。
其中，类AutoConfigurationImportSelector.class会加载spring-autoconfigure-metadata.properties，并且进行过滤筛选，将需要动态注入的类全路径交给AutoConfigurationPackages.Registrar.class进行初始化注入。
动态注入SpingBean
实现bean动态注入可以通过两种方式。
方案一：实现ImportSelector接口
/* @author Chris Beams
* @since 3.1
* @see DeferredImportSelector
* @see Import
* @see ImportBeanDefinitionRegistrar
* @see Configuration
*/
public interface ImportSelector {
/**
* Select and return the names of which class(es) should be imported based on
* the {@link AnnotationMetadata} of the importing @{@link Configuration} class.
*/
String[] selectImports(AnnotationMetadata importingClassMetadata);
}
方案二：实现ImportSelector接口
/* @author Chris Beams
* @since 3.1
* @see Import
* @see ImportSelector
* @see Configuration
*/
public interface ImportBeanDefinitionRegistrar {
/**
* Register bean definitions as necessary based on the given annotation metadata of
* the importing {@code @Configuration} class.
* @param importingClassMetadata annotation metadata of the importing class
* @param registry current bean definition registry
*/
void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry);
}
启用自动注入 使用注解@EnableAutoConfiguration开启自动注入功能。 @EnableAutoConfiguration @AutoConfigurationPackage @Import(AutoConfigurationImportSelector.class) public @interface EnableAutoConfiguration { // ignore... } @AutoConfigurationPackage @Import(AutoConfigurationPackages.Registrar.class) public @interface AutoConfigurationPackage { } Spring Boot通过AutoConfigurationImportSelector.class和AutoConfigurationPackages.Registrar.class这两个类配合使用，实现动态注入。 其中，类AutoConfigurationImportSelector.class会加载spring-autoconfigure-metadata.properties，并且进行过滤筛选，将需要动态注入的类全路径交给AutoConfigurationPackages.Registrar.class进行初始化注入。 动态注入SpingBean 实现bean动态注入可以通过两种方式。 方案一：实现ImportSelector接口 /* @author Chris Beams * @since 3.1 * @see DeferredImportSelector * @see Import * @see ImportBeanDefinitionRegistrar * @see Configuration */ public interface ImportSelector { /** * Select and return the names of which class(es) should be imported based on * the {@link AnnotationMetadata} of the importing @{@link Configuration} class. */ String[] selectImports(AnnotationMetadata importingClassMetadata); } 方案二：实现ImportSelector接口 /* @author Chris Beams * @since 3.1 * @see Import * @see ImportSelector * @see Configuration */ public interface ImportBeanDefinitionRegistrar { /** * Register bean definitions as necessary based on the given annotation metadata of * the importing {@code @Configuration} class. * @param importingClassMetadata annotation metadata of the importing class * @param registry current bean definition registry */ void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry); }