My controller/servlet with "/" mapping isn't overriding "Hello App Engine!"

Question

I'm working with Spring MVC on google app engine and even though I've gotten a basic hello world example working, I can't get my servlet to show up when I use the request mapping of "/". Even when I specify "/" as my request mapping in my controller, I keep getting the "Hello App Engine!" page with a link to my project. I've already pulled the welcome-file declaration out of my web xml.

Basically...

package my.package.for.spring.stuff.controllers;

import ....;

// It doesn't seem to make a difference if 
// I have this reqeustmapping or not...
@Controller
public class MainController {

  // If I change mapping to "/main" and then go to
  // localhost:8888/main then everything works as expected
  @RequestMapping("/")
  public String HelloWorld() {
    return "MyView";
  }
}

is still going to the "Hello App Engine!" page. Also, here is my web.xml...

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">


    <servlet>
        <servlet-name>SpringAppEngine</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringAppEngine</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
</web-app>

And then here is my spring xml...

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
        xmlns:context="http://www.springframework.org/schema/context"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd  
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

        <context:component-scan base-package="my.package.for.spring.stuff" />

        <bean id="viewResolver"
                class="org.springframework.web.servlet.view.InternalResourceViewResolver"
                p:prefix="/WEB-INF/views/main/" p:suffix=".jsp" />

</beans>

Why is the app engine generated welcome file still showing up even though I'm declaring the root mapping in my controller? I know my setup should be right because when I change the requestmapping, everything works as expected.

does it work if you change your mapping to something else? can you show your spring xml? — Igor Artamonov
Yes, it does work if I change the mapping to anything else and then go to localhost:8888/anythingelse. Im not at a place where I can get my other xmls. Ill have to post those later this evening. — Dave
I've updated the question w/my xmls and the class pretty much exactly as I'm using now. — Dave
Where does this "hello" string comes from? It could just be a bug in App Engine. If the text is in index.html or index.jsp, have you tried just deleting this html/JSP? — JB Nizet

JB Nizet JB Nizet · Accepted Answer · 2012-01-21T17:58:54

The servlet 3.0 spec says:

A string containing only the ’/’ character indicates the "default" servlet of the application.

And it also says:

By default all applications will have index.htm(l) and index.jsp in the list of welcome-file-list. The descriptor may to be used to override these default settings.

So, I guess that the container considers that the implicit index.html welcome file is an exact match, which takes precedence over the default servlet mapped to /.

The solution is to delete the index.html file or, probably, to define an explicit empty welcome file list in the descriptor.

My controller/servlet with "/" mapping isn't overriding "Hello App Engine!"

3 Answers