forwarding response to another action in struts and sending file in response

Question

I'm forwarding an action to from doFilter method conditionally as the following code to another method :

    public void dofilter(ActionMapping mapping, ActionForm actionForm, HttpServletRequest request,
                              HttpServletResponse resp) {
    String reportType = request.getParameter("reportType");
    ActionForward actionForward = null;
    try {

       if (reportType.equals("completedChart")) {
                actionForward = cmsGetCompeltedTasks(mapping, actionForm,request, resp);

    } catch (Exception ex) {
        ex.printStackTrace();
    }

}

and my method that accepts the action and the response is that generates a jasper report file and sends it in the response :

    public ActionForward cmsGetCompeltedTasks(ActionMapping mapping, ActionForm form, HttpServletRequest request,
                                          HttpServletResponse response) throws Exception {
            JasperReport jasperReport =                     fileName = COMPLETED_TASK + format.format(new Date()).toString() + ".xlsx";
                String filePath = servlet.getServletContext().getRealPath("") + fileName;
                System.out.println(filePath);
                JRXlsxExporter exporter = new JRXlsxExporter();
                exporter.setParameter(JRExporterParameter.JASPER_PRINT, jasperPrint);
                exporter.setParameter(JRExporterParameter.OUTPUT_FILE_NAME, filePath);
                exporter.exportReport();                
                response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
                response.addHeader("Content-Disposition", "attachment; filename=" + fileName);
                file = new File(filePath);
                FileInputStream fileInputStream = new FileInputStream(filePath);
                OutputStream responseOutputStream = response.getOutputStream();
                int bytes;
                while ((bytes = fileInputStream.read()) != -1) {
                    responseOutputStream.write(bytes);
                }
                responseOutputStream.flush();
                fileInputStream.close();
                 responseOutputStream.close();

        return mapping.findForward("cmsGetCompeltedTasks");


    } catch (Exception e) {
        e.printStackTrace();
    }           finally {
            file.delete();
        }

    return null;

}

But no file is downloading and I get an exception:

java.lang.IllegalStateException: Cannot forward after response has been committed

Answer 1

The problem was that I was firing Ajax request and I send the file to download in servlet response but the file to be download was handled by Ajax request in JavaScript on the success callback not the servlet response I handled the issue to send a direct URL to the file I want to download in the Ajax success call back and fire a new request to the that file specific URL.