How to send a file from a servlet the "right" way? - http

Question

I'm trying to send a file to a user from an http servlet.
The servlet runs some identification tests (on the request) and then sends the client a file.
This generally works but now I turned on my TOMCAT server redirects to https and when I try to access the servlet and download the file from either IE6 or IE8 it fails and I get this exception:
java.lang.IllegalStateException: Cannot forward after response has been committed
(on the localhost.log)
and
ClientAbortException: java.net.SocketException: Connection reset by peer: socket write error
(in the servlet log)
The code that does the sending (Simplified):
private void sendFile(HttpServletResponse response, byte[] file, String clientFileName)
{
ServletOutputStream op = null;
setContentType(response);
response.setHeader("Content-Disposition", "attachment; filename=\"" + clientFileName + "\"");
// send byte array to output buffer.
op = response.getOutputStream();
// Content Length must be set after all processing done.
response.setContentLength((int) file.length);
op.write(file);
}
Is this the correct way to send a file from a servlet? What's the best way?
Thanks!!
UPDATE
Used the code from #BalusC artice in this link:
http://balusc.blogspot.com/2007/07/fileservlet.html
This made it work.
Still doesn't work in IE6-IE8 when used from Gmail because of a filtering stage gmail adds to downloads in these browsers.
UPDATE 2
The problem seems to be with Gmail + Internet Explorer 6-8.
I'm Assuming that gmail is doing a redirect (That's actually pretty obvious if you look at the url on the page after you click the link in the mail).
Is Client-Pull technique my only solution?

Answer 1

The solution to the problem is the "Client-Pull" technique.
By adding a Refresh value to the header we make the browser ask for the file.
This is the only solution I could come up to that overcomes the fact the gmail will use redirection when pressing a link from within an email.
In the code I did this:
response.setHeader("Refresh", "3; URL=\"" + url.toString() + "\"");
forwardToJSP(request, response, "waitForBrowserRefreshPage.jsp");
Meaning - after 3 seconds ask the user for the specified url which will, in turn, deliver the file to the client.
The forwardToJSP method displays the "You will be forwarded soon, here a link if it fails" message.