I am learning spring which is being used in my project.I found the ContextLoaderListener entry in my web.xml . But could not figure out how exactly it helps the developer? In official doc of ContextLoaderListener it says it is to start WebApplicationContext . Regarding WebApplicationContext , api says Interface to provide configuration for a web application . But i am not able to understand what i am achieving with ContextLoaderListener which internally init the WebApplicationContext ?
As per my understanding, ContextLoaderListener reads the spring configuration file (with value given against contextConfigLocation in web.xml), parse it and loads the singleton bean defined in that config file. Similarly when we want to load prototype bean, we will use same webapplication context to load it. So we initialize the webapplication with ContextLoaderListener so that we read/parse/validate the config file in advance and whenever we wan to inject dependency we can straightaway do it without any delay. Is this understanding correct?
Your understanding is correct. The
ApplicationContext is where your Spring beans live. The purpose of the
ContextLoaderListener is two-fold:
to tie the lifecycle of the
ApplicationContext to the lifecycle of the
to automate the creation of the
ApplicationContext, so you don't have to write explicit code to do create it - it's a convenience function.
Another convenient thing about the
ContextLoaderListener is that it creates a
WebApplicationContext provides access to the
ServletContextAware beans and the