org.springframework.context.support.AbstractApplicationContext#refresh
org.springframework.context.support.AbstractApplicationContext#finishBeanFactoryInitialization

org.springframework.beans.factory.support.DefaultListableBeanFactory#preInstantiateSingletons

org.springframework.beans.factory.support.AbstractBeanFactory#getBean(java.lang.String)
获取Bean A
org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
-> doGetBean(A)
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String)
	没有则返回null
	org.springframework.beans.factory.support.DefaultListableBeanFactory#containsBeanDefinition
	查看BeanDefinition是否已存在BeanName的实例，没有则返回
	org.springframework.beans.factory.support.AbstractBeanFactory#markBeanAsCreated
	创建状态标记
	org.springframework.beans.factory.support.AbstractBeanFactory#getMergedLocalBeanDefinition
	获取BeanName本地合并的RootBeanDefinition
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, org.springframework.beans.factory.ObjectFactory<?>)
	获取单例Bean工厂对象
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])
	创建Bean
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
	执行Bean创建
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#addSingletonFactory
	A提前曝光对象 三级缓存BeanName到三级缓存工厂中【this.singletonFactories.put(beanName, singletonFactory);】
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean
	填充注入属性A的B 
	org.springframework.beans.factory.support.AbstractBeanDefinition#getPropertyValues
	【itBean】获取注入属性值
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyPropertyValues
	执行注入
	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveValueIfNecessary
	解析注入属性 -> doGetBean(B) doGetBean（A）

	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveReference
	解析运行时引用Bean
	org.springframework.beans.factory.support.AbstractBeanFactory#getBean(java.lang.String)
	获取Bean getBean(B) -> B提前曝光三级缓存池 ->注入B的属性A -> 解析运行时引用A ->getBean(A)

	致此，实例化A、B到了三级缓存池，继续getBean(A)【A.B.A】

	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
	从单例获取B实例的属性A Bean 【三级缓存取空，二级缓存取空，三级缓存工厂取BeanName,singletonFactory.getObject(),getEarlyBeanReference】
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#getEarlyBeanReference
	获取到三级缓存暴露的Bean A
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
	将Bean A存入二级缓存中，移除BeanName A 在三级缓存工厂的工厂
	org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
	获取到A的属性B中的A Bean
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#getObjectForBeanInstance
	org.springframework.beans.factory.support.AbstractBeanFactory#getObjectForBeanInstance
	获取Bean A实例  返回getBean(A)
	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveReference
	返回A.b.a 的运行时引用解决
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#registerDependentBean
	注册依赖Bean dependenciesForBean.add(BeanAName)
	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveValueIfNecessary
	返回A.b.a属性解析
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyPropertyValues
	返回执行属性注入
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean
	返回A.B.A填充
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
	返回A.B Bean创建，此时已完成B的A填充，将开始初始化A.B
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#initializeBean(java.lang.String, java.lang.Object, org.springframework.beans.factory.support.RootBeanDefinition)
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeAwareMethods
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyBeanPostProcessorsBeforeInitialization
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeInitMethods
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyBeanPostProcessorsAfterInitialization
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
	返回A.B的初始化
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
	获取A.B的单例 null
	org.springframework.beans.factory.support.AbstractBeanFactory#registerDisposableBeanIfNecessary
	返回A.B的实例
	org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, org.springframework.beans.factory.ObjectFactory<?>)
	返回singletonFactory生成的单例
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#addSingleton
	将A.B设入三级缓存，移除三级缓存工程A.BName的工厂

	org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
	返回A.B的getSingleton 单例获取
	org.springframework.beans.factory.support.AbstractBeanFactory#getObjectForBeanInstance
	返回A.B 实例对象
	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveReference
	返回A的属性B运行时引用解析
	此时填充A.B成功
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#registerDependentBean
	注册A.B依赖
	org.springframework.beans.factory.support.BeanDefinitionValueResolver#resolveValueIfNecessary
	返回A.B属性解析
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#applyPropertyValues
	返回A.B属性填充执行中
	org.springframework.beans.AbstractPropertyAccessor#setPropertyValues(org.springframework.beans.PropertyValues, boolean, boolean)
	属性注入
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean
	返回A的属性填充中
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
	返回A Bean的创建中
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#initializeBean(java.lang.String, java.lang.Object, org.springframework.beans.factory.support.RootBeanDefinition)
	A Bean初始化 -> 返回A的创建中
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
	A Bean单例获取 null  返回Bean
	org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBean(java.lang.String, org.springframework.beans.factory.support.RootBeanDefinition, java.lang.Object[])
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, org.springframework.beans.factory.ObjectFactory<?>)
	org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#addSingleton
	将A设入三级缓存中 移除三级缓存工厂Aname 移除二级缓存Aname 
	
	org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
	返回
	org.springframework.beans.factory.support.AbstractBeanFactory#getObjectForBeanInstance
	org.springframework.beans.factory.support.AbstractBeanFactory#getBean(java.lang.String)

org.springframework.beans.factory.support.DefaultListableBeanFactory#preInstantiateSingletons
循环完成第一个Bean A的实例化

org.springframework.beans.factory.support.DefaultListableBeanFactory#preInstantiateSingletons
开启第二个Bean B的遍历
org.springframework.beans.factory.support.AbstractBeanFactory#isFactoryBean(java.lang.String)
是否工厂Bean
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
获取Bean B 单例 返回 是否工厂Bean false
org.springframework.beans.factory.support.AbstractBeanFactory#getBean(java.lang.String)
获取Bean B
org.springframework.beans.factory.support.AbstractBeanFactory#doGetBean
执行Bean B获取
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry#getSingleton(java.lang.String, boolean)
获取Bean B 单例 null 直接返回
org.springframework.beans.factory.support.DefaultListableBeanFactory#preInstantiateSingletons
循环遍历结束

此时 singletonObjects 单例池中Bean A\B  三级缓存工厂 0  二级缓存单例池 0