The support for @Controller and @RequestMapping is provided by Spring by default. However, by enabling mvc:annotation-driven you get support for processing the requests that are mapped to annotated controller methods, such as declarative validation, formatting and conversion service.
In servlet-config.xml
<mvc:default-servlet-handler/>
<mvc:annotation-driven />
In WEB.xml
<servlet-mapping>
<servlet-name>home</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>