SpringBoot源码之finishBeanFactoryIn

refresh方法中finishBeanFactoryInitialization方法用来实例化所有的单例bean。
具体流程如下：
start -> getBean -> doGetBean -> getSingleton -> CreateBean -> resolveBeforeInstantiation
-> doCreateBean -> createBeanInstance -> instantiateBean -> instantiate -> populateBean
-> initializeBean