Question

    String contenttype = rs.getString("contentType");
    String filename = rs.getString("fileName");

    response.setContentType(contenttype);
    response.setHeader("Content-disposition","attachment;filename=" + filename.replace('"', ' '));


    java.io.InputStream instream = rs.getBinaryStream("fileData");
    byte[] b = new byte[1000];
    while (instream.read(b) > 0) {
        try {
            response.getOutputStream().write(b);
        }
        catch(Exception e) {}
    }

    try {
        response.getOutputStream().flush();
    }
    catch(Exception e) {}

Answer 1

Normally, it should allow calling response.getOutputStream() any number of times. I think you are calling both response.getOutputStream() and response.getWriter().

Please check if you are calling response.getWriter() anywhere or is the request is landing in JSP which writes to response.getWriter().