JSP Including A Private Servlet

Question

I have a servlet that responds to a URL and then forwards to a JSP in a typical MVC pattern.

Many pages share the same page head so in the JSP there is an include to head.jsp

head.jsp is placed inside WEB-INF so that it cannot be accessed directly.

Now I find that I need to add some control to the head. Rather than forwarding to WEB-INF/head.jsp and putting scriptlets in I would like to forward to a servlet instead.

How can I forward from the JSP to a servlet without mapping that servlet to a URL as I do not want to give direct access to this servlet.

Or to put it another way is there a servlet equivalent of WEB-INF to hide it from direct access? So the servlet can only be called via an include?

Arjan Tijms Arjan Tijms · Accepted Answer · 2011-12-12T21:34:38

Rather than forwarding to WEB-INF/head.jsp and putting scriptlets in I would like to forward to a servlet instead.

It's indeed possible to do this (using <jsp:include> or a small scriptlet that dispatches), but I'm not sure whether this is really the best approach. The Servlet would either write directly to the response or would put some data in the request scope that the JSP can pick up later.

Writing directly to the response is a bit debatable today and for the other approach you don't need a Servlet at all.

The idiomatic way is to use some helper bean that contains the logic. The original Servlet you mentioned can put this bean into request scope, or you can use the <jsp:usebean> tag. Reference the data the helper bean prepared via expression language or very simple scriptlets.

So the servlet can only be called via an include?

If you still want to go this route, there might be an option of securing the Servlet behind a role and then giving the head.jsp a run-as role in web.xml:

<servlet>
    <servlet-name>headInclude</servlet-name>
    <jsp-file>/WEB-INF/head.jsp</jsp-file>
    <run-as>
        <role-name>SYSTEM</role-name>
    </run-as>
</servlet>

disclaimer: I have never tried this myself, just pointing in a possible direction.

JSP Including A Private Servlet

1 Answers