关于 "static" 首先对比 BeanDefinition : 加 static BeanDefinition 中 factoryBeanName=null; 不加 static BeanDefinition 中 factoryBeanName=annotationDependencyInjectionResolutionDemo; 上代码： org.springframework.beans.factory.support.ConstructorResolver#instantiateUsingFactoryMethod 中，下面代码片段： String factoryBeanName = mbd.getFactoryBeanName(); if (factoryBeanName != null) { if (factoryBeanName.equals(beanName)) { throw new BeanDefinitionStoreException(mbd.getResourceDescription(), beanName, "factory-bean reference points back to the same bean definition"); } factoryBean = this.beanFactory.getBean(factoryBeanName); // 此处会去先创建类对象，导致注入失败 if (mbd.isSingleton() && this.beanFactory.containsSingleton(beanName)) { throw new ImplicitlyAppearedSingletonException(); } factoryClass = factoryBean.getClass(); isStatic = false; } else { // It's a static factory method on the bean class. if (!mbd.hasBeanClass()) { throw new BeanDefinitionStoreException(mbd.getResourceDescription(), beanName, "bean definition declares neither a bean class nor a factory-bean reference"); } factoryBean = null; factoryClass = mbd.getBeanClass(); isStatic = true; } 不加 static，会在创建 Bean beanPostProcessor 的过程中「未创建完成」，先去创建所在类的实例，由于处理 @Autowired 等注解的后置处理器未完成创建，导致字段注入失败。

总结:当demo bean对象初始化时,自定义的beanPostProcessors还未被加载所以不能解析@InjectionUser注解的注入,可以通过static来让静态方法属于类而不实例(即不需要等待demo bean的初始化即可用),因为AnnotationConfigUtils#registerAnnotationConfigProcessors()方法,定义了beanDefinitionRegistry中如果存在AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME bean对象后就不在去创建默认的bean对象,所以当我们将bean的名称改为AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME时对应的@autowired @value @inject注解都不会被解析,此时只有@injectionUser被解析,如果我们不将bean名称改为AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME此时两个AutowiredAnnotationBeanPostProcessor同时存在自定义注解@injectionUser和@Autowired同时可以被解析 老师有个问题,就是当自定义bean定义为非静态时,此时默认的AutowiredAnnotationBeanPostProcessor会被初始化,但是为啥demo对象实例化的时候对应的user等非@InjectionUser修饰的主键的属性未被依赖注入呢?

@Configuration public class AutowiredAnnotationDependency { @Bean @Order(Ordered.LOWEST_PRECEDENCE - 3) public static AutowiredAnnotationBeanPostProcessor definedAutowire() { AutowiredAnnotationBeanPostProcessor beanPostProcessor = new AutowiredAnnotationBeanPostProcessor(); Set<Class<? extends Annotation>> autowiredAnnotationTypes = new LinkedHashSet<>(4); autowiredAnnotationTypes.add(MyAutowired.class); autowiredAnnotationTypes.add(Autowired.class); autowiredAnnotationTypes.add(Value.class); autowiredAnnotationTypes.add(Inject.class); beanPostProcessor.setAutowiredAnnotationTypes(autowiredAnnotationTypes); return beanPostProcessor; } } @Component public class AnnotationLookup { @Autowired private User user; @Autowired private Map<String, User> userMap; @MyAutowired private Optional<ChildUser> optionalUser; @Autowired private ObjectProvider<User> userObjectProvider; @Qualifier("childUser") @Inject private User injectUser; } 马哥，在boot工程下没有加static为什么是可以的？