有以下几个疑问？

基于xml的方式我们知到，填充bean属性阶段将xml中定义的值填入。那么问题：@Autowire注解的属性何时注入？也是填充bean属性阶段？

答：是的属性填充都是在填充阶段，即 populateBean方法中进行的
@Autowire、@Resource等如何实现属性注入的呢？

答：定义特殊的BeanPostProcessor，这些BeanPostProcessor是MergedBeanDefinitionPostProcessor和InstantiationAwareBeanPostProcessor的子类在填充阶段就开始使用了。
Spring中开启注解的配置是<context:annotation-config/> ，那它的作用是啥？

这个配置的作用就是引入上面所说的特殊的BeanPostProcessor，来完成对注解的解析主要有： AutowiredAnnotationBeanPostProcessor CommonAnnotationBeanPostProcessor PersistenceAnnotationBeanPostProcessor RequiredAnnotationBeanPostProcessor ———————————————— 版权声明：本文为CSDN博主「Beckio」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。原文链接：https://blog.csdn.net/Beckio/article/details/79421335

调用途径解析

函数式接口，作为一个入参传入getSingleton()方法中 ```java @FunctionalInterface public interface ObjectFactory {

/**
- Return an instance (possibly shared or independent)
- of the object managed by this factory.
- @return the resulting instance
- @throws BeansException in case of creation errors */ T getObject() throws BeansException;

}


2. `getSingleton`方法在方法内部，会调用这个lamda，实际进入`return createBean`这句
```java
sharedInstance = getSingleton(beanName, () -> {
    //getSingleton 最终是触发这个 方法的一个调用
    try {
        //createBean
        return createBean(beanName, mbd, args);
    }
    catch (BeansException ex) {
        // Explicitly remove instance from singleton cache: It might have been put there
        // eagerly by the creation process, to allow for circular reference resolution.
        // Also remove any beans that received a temporary reference to the bean.
        destroySingleton(beanName);
        throw ex;
    }
                    });

createBean方法最后进入doCreateBean就是整个Bean的创建阶段的生命周期

生命周期-创建阶段

protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
    throws BeanCreationException {
    // Instantiate the bean.
    BeanWrapper instanceWrapper = createBeanInstance(beanName, mbd, args);
    addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
    populateBean(beanName, mbd, instanceWrapper);
    exposedObject = initializeBean(beanName, exposedObject, mbd);
    //判断提前引用出去的对象，是否有地址上的变化
    if (earlySingletonExposure) {
    }
    //注册实现了DisposableBean的bean
    registerDisposableBeanIfNecessary(beanName, bean, mbd);
    return exposedObject;
    }

实例化bean对象
提前暴露bean对象在三级缓存中
填充属性

初始化bean

protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
 invokeAwareMethods(beanName, bean);
 wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
 invokeInitMethods(beanName, wrappedBean, mbd);
 applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
 return wrappedBean;
}

调用Aware接口的实现方法

调用BeanPostProcessor的postProcessBeforeInitialization方法

public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
       throws BeansException {
   Object result = existingBean;
   for (BeanPostProcessor processor : getBeanPostProcessors()) {
       Object current = 
           processor.postProcessBeforeInitialization(result, beanName);
       if (current == null) {
           return result;
       }
       result = current;
   }
   return result;
}

调用初始化方法

调用BeanPostProcessor的postProcessAfterInitialization方法

@Override
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
       throws BeansException {
   Object result = existingBean;
   for (BeanPostProcessor processor : getBeanPostProcessors()) {
       Object current = processor.postProcessAfterInitialization(result, beanName);
       if (current == null) {
           return result;
       }
       result = current;
   }
   return result;
}

判断提前被引用的bean对象是否有变化
若实现了DisposableBean则注册一下

雨润工作笔记

Bean的生命周期

调用途径解析

生命周期-创建阶段