/**
* Abstract implementation of the {@link org.springframework.context.ApplicationContext}
* interface. Doesn't mandate the type of storage used for configuration; simply
* implements common context functionality. Uses the Template Method design pattern,
* requiring concrete subclasses to implement abstract methods.
*
* <p>In contrast to a plain BeanFactory, an ApplicationContext is supposed
* to detect special beans defined in its internal bean factory:
* Therefore, this class automatically registers
* {@link org.springframework.beans.factory.config.BeanFactoryPostProcessor BeanFactoryPostProcessors},
* {@link org.springframework.beans.factory.config.BeanPostProcessor BeanPostProcessors}
* and {@link org.springframework.context.ApplicationListener ApplicationListeners}
* which are defined as beans in the context.
*
* <p>A {@link org.springframework.context.MessageSource} may also be supplied
* as a bean in the context, with the name "messageSource"; otherwise, message
* resolution is delegated to the parent context. Furthermore, a multicaster
* for application events can be supplied as "applicationEventMulticaster" bean
* of type {@link org.springframework.context.event.ApplicationEventMulticaster}
* in the context; otherwise, a default multicaster of type
* {@link org.springframework.context.event.SimpleApplicationEventMulticaster} will be used.
*
* <p>Implements resource loading through extending
* {@link org.springframework.core.io.DefaultResourceLoader}.
* Consequently treats non-URL resource paths as class path resources
* (supporting full class path resource names that include the package path,
* e.g. "mypackage/myresource.dat"), unless the {@link #getResourceByPath}
* method is overwritten in a subclass.
今天看spring的代码，AbstractApplicationContext中的注释有提到Template Method design pattern ，就查了一下这种设计模式。
参考：https://blog.****.net/qq_24692041/article/details/60961880
这种设计模式，就是在父类中定义处理流程的框架，在子类中实现具体的处理方式。我的理解是，父类处理步骤，子类处理数据。其中父类的方法基于里氏转换原则，要final掉。