response.setContentType() getting reset in Java Filter [duplicate]

Answer 1

First of all, you should always call (or have very good reason not to do so)

 filterChain.doFilter(request, response);

or filters declared after this one will not be called.

Next, move call filterChain.doFilter() to the top of method, set your headers after and declare your filter mapping as last in web.xml. And this will work as expected.

Answer 2

I solved it with the help of this answer:

private class ForcableContentTypeWrapper extends HttpServletResponseWrapper
{
    public ForcableContentTypeWrapper(HttpServletResponse response)
    {
        super(response);
    }

    @Override
    public void setContentType(String type)
    {
    }
    public void forceContentType(String type)
    {
        super.setContentType(type);
    }
}

Then changed my above code to:

    if (reqUrl.endsWith(gzExt))
    {
        ForcableContentTypeWrapper newResponse = new ForcableContentTypeWrapper(response);
        newResponse.setHeader("Content-Encoding", "gzip");
        newResponse.forceContentType("text/javascript");
        filterChain.doFilter(request, newResponse);
        return;
    }

Its not a pretty workaround, but it works.