Spring中提供一些Aware相关的接口，BeanFactoryAware、 ApplicationContextAware、ResourceLoaderAware、ServletContextAware等等，其中最常用到的是ApplicationContextAware。实现ApplicationContextAware的Bean，在Bean被初始后，将会被注入 ApplicationContext的实例。ApplicationContextAware提供了publishEvent()方法，

The controllability and observability play an important role in the design of control ... The importance of modern control theory lies in its ability to do the perfect design ... Observer design has been discussed because of the need for inaccessible

使用观察者模式的一个关于简单的推送天气预报的代码-Observer pattern using a code on the simple push Weather forecast