ClassPathXmlApplicationContext start 方法

https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/context/support/AbstractApplicationContext.html#start--  官方文档

http://stackoverflow.com/questions/24145070/use-of-start-method-in-classpathxmlapplicationcontext   其他网站搜索得到的

简单copy过来，只是为了记录一下。正确与否不知道。。

Spring provides a ApplicationListener interface to listen for various ApplicationEvents. One such event is the ContextStartedEvent. You can create a bean of some class that implements ApplicationListener.

When you invoke start(), the ApplicationContext will publish such an event and allApplicationListener beans registered for ContextStartedEvent (they get registered automatically if found in the context) will get notified.

If you don't call start(), they will not get notified.