How is Spring actually bootstrap?

Question

1. Does anybody know how Spring is actually bootstraps?
2. Which instances created and by whom?
3. I really want to know who creates instances of WebApplica

Answer 1

See http://docs.spring.io/spring/docs/4.0.x/spring-framework-reference/htmlsingle/#context-create.

The principle is to declare a ServletContextListener in the standard webapp descriptor (web.xml). Such a listener is indeed instantiated by the container and is called when the application is initialized and when it's destroyed.

Spring provides such a ServletContextListener: ContextLoaderListener which, as its name indicates, loads a Spring context when the webapp is initialized.