What is DispatcherServlet and ContextLoaderListener?

Ref:- http://howtodoinjava.com/2015/03/02/spring-mvc-interview-questions-with-answers/

Spring’s web MVC framework is, like many other web MVC frameworks, request-driven, designed around a central Servlet that handles all the HTTP requests and responses. Spring’s DispatcherServlet however, does more than just that. It is completely integrated with the Spring IoC container so it allows you to use every feature that Spring has.

After receiving an HTTP request, DispatcherServlet consults the HandlerMapping (configuration files) to call the appropriate Controller. The Controller takes the request and calls the appropriate service methods and set model data and then returns view name to the DispatcherServlet. The DispatcherServlet will take help from ViewResolver to pickup the defined view for the request. Once view is finalized, The DispatcherServlet passes the model data to the view which is finally rendered on the browser.

<web-app>   <display-name>Archetype Created Web Application</display-name>       <servlet>         <servlet-name>spring</servlet-name>             <servlet-class>                 org.springframework.web.servlet.DispatcherServlet             </servlet-class>         <load-on-startup>1</load-on-startup>     </servlet>       <servlet-mapping>         <servlet-name>spring</servlet-name>         <url-pattern>/</url-pattern>     </servlet-mapping>       </web-app>

By default, DispatcherServlet loads its configuration file using <servlet_name>-servlet.xml. E.g. with above web.xml file, DispatcherServlet will try to find spring-servlet.xml file in classpath.

ContextLoaderListener reads the spring configuration file (with value given against “contextConfigLocation” in web.xml), parse it and loads the beans defined in that config file. e.g.

<servlet>     <servlet-name>spring</servlet-name>     <servlet-class>         org.springframework.web.servlet.DispatcherServlet     </servlet-class>           <init-param>         <param-name>contextConfigLocation</param-name>         <param-value>/WEB-INF/applicationContext.xml</param-value>     </init-param>           <load-on-startup>1</load-on-startup> </servlet>