调用方
/org/springframework/beans/factory/support/AbstractBeanFactory.java:333

					sharedInstance = 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