Servlet filter that can differentiate between Filter and Servlet Writers

Question

Hey,
I'm trying to build a Filter and HttpServletResponseWrapper that, when applied to a generic servlet, can differentiate between the output stream from the Servlet and the one from the Filters.
So, say I have a servlet:
PrintWriter pw = response.Writer();
pw.write( "Output from servlet" );
pw.close();And a filter that is applied to the servlet:
PrintWriter pw = response.Writer();
pw.write( "Output from filter" );
pw.close();I want to be able to do this in my filter that is able to differentiate between the servlet and filter response:
System.out.println( "Response from servlet: " + responseWrapper.servlet.toString() );
System.out.println( "Response from filter: " + responseWrapper.filter.toString() );The responseWrapper.servlet and responseWrapper.filter can contain all filter responses from all the servlet(s) and filter(s), respectively.
Can anyone give me guidance as to how to start with this - really I just need to know if I can differentiate between servlet and filter responses in a generic way (without having to modify the response specially in the filter or servlet files that write output)
Thanks for your time.

Answer 1

first thing's first..if the OutputStream if not closed Either a Filter or a ServletChain can write on to the stream.
There could be cases where the servletoutputstream would be closed at servlet end itself.Therefore,its a valiant effort by acomplishing a responseheader in the response to indicate that.
Now once the response/outputstream is not closed or flushed out there is not direct way by which you do this unless we indicate using response Headers as flags when we are implementing FilterChaning.
Hope that might help :)
REGARDS,
RaHuL