BeanFactoryPostProcessor的典型应用:PropertyPlaceholderConfigurer
BeanFactoryPostProcessor会在所有的bean配置载入之后执行(即:applicationContext.xml解析完成之后)
BeanFactoryPostProcessor接口
public interface BeanFactoryPostProcessor {
void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException;
}