刪除bean后@Autowired（required = false）失敗

Question

在https://github.com/nowszy94/Autowired-null上重現的步驟

使用BeanDefinitionRegistry:removeBeanDefinition方法從Spring上下文中刪除bean后，@ @Autowired(required = false) spring throws error：

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'helloService' is defined
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:698) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1175) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:284) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.resolvedCachedArgument(AutowiredAnnotationBeanPostProcessor.java:508) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.access$200(AutowiredAnnotationBeanPostProcessor.java:115) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:538) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.2.7.RELEASE.jar:4.2.7.RELEASE]

Answer 1

自動裝配發生在bean創建時。 如果您沒有定義helloService bean，那么在bean創建期間嘗試滿足該依賴項時，spring應用程序不會拋出異常。 在您的示例中，您將從應用程序上下文中將helloService bean連接到HelloController bean之后將其刪除。