Why can't I delete the file?

Question

What I want to do is: After user download the file from web, the application will delete the file automatically on ther server. However, the delete function cannot work which it prompts the java.lang.Exception, I suspent it is the download process hold the file, how can I solve it?
DownloadReport(request, response, reportFile);
Utility.deleteFile(reportFile);
     public void DownloadReport(HttpServletRequest request,
               HttpServletResponse response, String reportFile) throws Exception {
          File fFile = new File(reportFile);
          String stFileName = fFile.getName();
          response.setContentType("application/vnd.ms-excel");
          response.setHeader("Content-Disposition", "attachment;filename=\""
                    + stFileName + "\"");
          // System.out.println("Henry "+getServletContext());
          InputStream isStream = null;
          try {
               PrintWriter out = response.getWriter();
               isStream = new FileInputStream(fFile);
               int i;
               while ((i = isStream.read()) != -1) {
                    out.write(i);
               isStream.close();
               out.close();
          } catch (Exception ioeException) {
               log.error("Download report error", ioeException);
               ioeException.printStackTrace();
               throw new ServletException("Download report error", ioeException);
     public static void deleteFile(String path) {
          boolean deleted = false;
          try {
               File delefile = new File(path);
               if (delefile.exists())
                    deleted = delefile.delete();
               if (deleted == false)
                    throw new Exception("File could not be deleted " + path);
          } catch (Exception e) {
               e.printStackTrace();
     }

Answer 1

Hi, my application is using POI API generating the Excel report, after genration, the report will be stored on the server, and then user download the report to their local machine throught web and then I delete the report on the server. I don't quitely understand what you mean, could you kindly explain to me detailly:p. Btw, I have tried to print out the exception, but it only shows "java.lang.Exception: File could not be deleted " which is so limited. If I comment the DownReport function, the file could be deleted successfully. But if it happens after the download action, it is failed.