Spring源码阅读：IOC容器的设计与实现（二）——ApplicationContext

/**

 * 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.

 */