modify response buffer

Hi list,

I would like to overwrite the response buffer with a complete new string 
within onResponse. As has been suggested here [1], i should simply call 
res.reset. But this also reset all response headers, that i've already 
set. Is there a simple way to preserve them?

Currently I write sthg like:
   var contentType = res.contentType;
   var charset = res.charset;
   var cache = res.cache;
   // FIXME: I need to preserve all existing headers
   // in particular cookies that are being set
   res.reset();
   res.contentType = contentType;
   res.charset = charset;
   res.cache = cache;
   res.write(str);

A method like res.setBuffer (like [2]) would come in handy for such a task.

greets,
  michi


[1] http://helma.org/pipermail/helma-dev/2007-January/003249.html
[2] 
http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/servlet/ServletResponse.html#resetBuffer()