How to use Filter/Responsewrapper to trap http response

Question

My application deals with various request/responses. How do i write a Responsewrapper or responseoutputstream to trap the contents of the response in a file without fiddling with the actual servletoutputstream, which is thrown back to the browser as usual.

Answer 1

Thanks for the answers,
I am using something like this in my filter code
ByteArrayOutputStream baos = new ByteArrayOutputStream();
CacheResponseWrapper wrappedResponse = new CacheResponseWrapper(hres, baos);
chain.doFilter(hreq, wrappedResponse);
FileOutputStream fos = new FileOutputStream(file);
fos.write(baos.toByteArray());
fos.flush();
fos.close();
FileInputStream fis = new FileInputStream(ile);
String mt = sc.getMimeType(hreq.getRequestURI());
response.setContentType(mt);
ServletOutputStream sos = hres.getOutputStream();
for (int i = fis.read(); i!= -1; i = fis.read()) {
     sos.write((byte)i);
The CacheResponseWrapper uses a CacheResponseStream which write the necessary bytes to the provided ByteArrayOutputStream instead of the general ServletOutputStream