A fourth solution (also portable) is to look at the Filter capability in
the servlet 2.3 API (supported by Tomcat 4.0).
Craig McClanahan
On Thu, 26 Apr 2001, Sasha Haghani wrote:
> Hi there,
>
> ------
> DISCLAIMER: This a Tomcat question, where the solution will likely require
> some tinkering with the implementation. What I'm to do is probably a
> non-standard use case. I think knowledge of the Tomcat internals is
> required to answer this. I hope this question is appropriate for this list
> -- if not I apologize in advance. Also, sorry for the length...
> ------
>
> I'd like to be able to invoke a JSP on-demand from a Java class and redirect
> the response output stream to a String. This could be used to dynamically
> generate the body of an e-mail, for instance. The key difference is that
> there isn't a *real* corresponding HTTP request or browser socket connection
> which would trigger JSP compilation and execution.
>
> I've come up with 3 potential solutions. Any input or comment on these from
> this list is much appreciated.
>
> ------
> SOLUTION 1: Connect to the Servlet Engine like a browser using a
> URLConnection object and retrieve the response from there.
>
> -> This solution is probably the most portable (across Servlet Engines) but
> likely isn't the most performant.
>
> ------
> SOLUTION 2: Using Tomcat Interceptors.
>
> -> I don't know anything about these but would there be anyway to catch and
> redirect the response using an Interceptor. I assume such a solution would
> only work with Tomcat.
>
> ------
> SOLUTION 3: A custom Interceptor Servlet with a custom Response object.
>
> -> A custom method could be called on such a GenericServlet and these
> servlet would include the body of the JSP using the
> RequestDispatcher.include method. A custom Response object would output the
> Writer stream to a String or StringBuffer.
>
> I've attached some sample source code which outlines what I have in mind.
>
> Could someone give me a reality check on whether this is even feasible or
> advisable. Particularly with regard to rolling my own Response
> implementation which redirects Writer to a String. Would this kind of
> kludge cause any problems for Tomcat?
>
> ------
> Any comments, help or suggestions that anyone can provide are much, much
> appreciated. Also, I'd love to hear alternative solutions. Thanks so much.
>
>
> Regards,
>
> Sasha Haghani,
> Toronto, Canada.
>
