In a Spring-based application, our application objects will live within an object container. This container will create objects and associations between objects and manage their complete lifecycle. These container objects are called Spring managed beans (or simply beans) and the container is called application context in the Spring world.

Spring's container uses dependency injection (DI) to manage the beans that make up an application. An application context (org.springframework.context.ApplicationContext) creates beans, associates beans together based on bean configuration, and dispenses beans upon request. A bean configuration can be defined via an XML file, annotation, or even via Java configuration classes. We are going to use annotation and Java configurations in our chapters.

A web application context is an extension of the application context, and is designed to work with the standard servlet context (javax.servlet.ServletContext). The web application context typically contains front-end related beans such as views and view resolvers, and so on. In the first chapter, we simply created a class called WebApplicationContextConfig, which is a bean configuration for our web application.

We learned that WebApplicationContextConfig is nothing but a Java-based bean configuration file for our web application context, where we can define the beans to be used in our application. Usually, we define beans using the @Bean annotation. In order to run a Spring MVC application successfully, Spring needs at least a bean that implements the org.springframework.web.servlet.ViewResolver interface. One such bean we defined in our web application context is InternalResourceViewResolver.