Map / (root URL) in Spring MVC

Question

This is something that I think should be very easy, but so far I have not been able to get it to work.

What I want to do is map my root path to a Spring MVC Controller. With a normal Servlet, I would just add a mapping for "/" in my web.xml, and it would pick it up quite well. But with Spring MVC, not so much.

I have tried many combinations, but none seem to work. I think the following one should work.

In web.xml:

<servlet-mapping>
    <servlet-name>myDispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

In my contextConfigLocation file:

<bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
    <property name="alwaysUseFullPath" value="true"/>
    <property name="mappings">
        <util:map>
            <entry key="/" value-ref="rootController"/>
        </util:map>
    </property>
</bean>

<bean id="rootController" class="my.package.RootController">

Then obviously, there is the case of the controller itself. I have no clue how to map the method to the actual root path. My attempt is something like this:

public class RootController extends MultiActionController {

    @RequestMapping("/")
    public ModelAndView display(HttpServletRequest request, HttpServletResponse response) throws Exception {

        final Map<String, Object> model = new HashMap<String, Object>();
        model.put("someVariable", "Hello, MVC world.");
        return new ModelAndView("rootPage", model);
    }
}

So let's say my application runs on http://localhost:8080/app/, I want that exact URL to execute the method display. I do not want to type anything after /app/. In fact, some things after /app/ are mapped to other controllers, and that all works fine (and they have to keep working).

What am I missing here? Why is this not simply working? If I use the same url-pattern to map to a plain Servlet instance, it works fine and I reach the doGet method, but with Spring MVC I seem to missing some particular black magic to get this to work.

Solution 1

Instead of mapping to / you can declare a welcome page in your web.xml file:

<welcome-file-list>
    <welcome-file>welcome.htm</welcome-file>
</welcome-file-list>

so your / path will be processed as /welcome.htm and then if your controller is correctly mapped to /welcome.htm it will process / as if it was a /welcome.htm request, without making changes to other configuration.

Solution 2

I'd recommend getting rid of the SimpleUrlHandlerMapping and just doing the following:

@Controller
@RequestMapping("/")
public class RootController
{
  @RequestMapping(method=RequestMethod.GET)
  public ModelAndView display(...)
  {
    ...
  }
}

This should get the result you want. Also, add <mvc:annotation-driven/> to your servlet context with a <context:component-scan base-package="some.package.path.to.controller" /> to have Spring wire up that controller.

Otherwise, you can probably map the URL with the SimpleUrlHandlerMapping as so:

<property name="mappings">
    <value>
        /*=rootController
    </value>
<property>

If done this way, you can keep the bean defined for rootController.