How can I map a "root" Servlet so that other scripts are still runnable?

user_76835 0
Viewed 33443

I'm trying to build a Servlet that calls a JSP page similar to the following:

public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws IOException, ServletException {
    req.getRequestDispatcher("/WEB-INF/main.jsp").forward(req, resp);
}

I need this Servlet to respond to the domain's root (eg: http://example.com/) so I'm using the following mapping in the web.xml:

<servlet-mapping>
    <servlet-name>MainServlet</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

The problem I'm having is that this matches EVERYTHING, so when the dispatcher forwards to "/WEB-INF/main.jsp" this matches the url-pattern so the Servlet gets run again. This results in a loop that runs until it dies with a java.lang.StackOverflowError.

How can I match the root without preventing other scripts from being runnable?

google-app-engine web.xml servlets java
8 Answers

Using the welcome-file element of web.xml worked for me, on app engine. Here's mine:

<web-app>
    <servlet>
        <servlet-name>RootServlet</servlet-name>
        <servlet-class>com.foo.RootServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>RootServlet</servlet-name>
        <url-pattern>/foo</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>foo</welcome-file>
    </welcome-file-list>
</web-app>
Jeb_318300

You can create a welcome file named index.jsp in the root with the following code using JSTL or otherwise.

<c:redirect url="/main"/>

So in the web.xml file you will have this:

<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>        
</welcome-file-list>

So anyone requesting the root will be redirected to /main. Now your servlet can be mapped to main.

<servlet-mapping>
    <servlet-name>MainServlet</servlet-name>
    <url-pattern>/main</url-pattern>
</servlet-mapping>
Vincent_Ramdhanie_274390

Try just to remove '*' from the pattern, i.e.

<url-pattern>/</url-pattern>
Gennady_Shumakher_425120

You can't redirect to WEB-INF. A servlet container will never serve requests for documents in that folder.

If you want your application (not just a servlet, but the entire application) to be available under the root context ("/" of "http://www.domainname.com/"), then you need to set up a context entry for it - not a servlet mapping.

With Tomcat, you add a new <Context> mapping (in one of about 3 different possible places).

user_42490

Have you tried the below? (Note the missing *, which is a wild card and is the reason that your configuration catches everything.)

<servlet-mapping>
        <servlet-name>MainServlet</servlet-name>
        <url-pattern>/index.jsp</url-pattern>
</servlet-mapping>

(Edited as per comments from just /.)

user_29610
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