调用方
/org/springframework/beans/factory/support/AbstractBeanFactory.java:333sharedInstance = getSingleton(beanName, () -> {try {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;}});

函数式接口

@FunctionalInterface
public interface ObjectFactory<T> {/*** 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;}

查看代码时的一点注意事项

通过ObjectFactory#getObject方法的实现是找不到具体的执行代码的,

只能通过方法DefaultSingletonBeanRegistry#getSingleton的调用来源去找具体的执行代码

个人的一点理解:

通过函数式编程,我们可以在不传递参数的前提下完成方法的回调

使得代码更加整洁

这里有函数式接口的一些介绍

Java特性函数式接口注解@FunctionalInterface浅析-CSDN博客