Question

I have written a code for downloading a file(blob in database table).I get a prompt while downloading but when i download it’s size increases and opens as a blank file or corrupted file.The controller calling 2 service methods downloadfile():- to get the blob type into a byte array.

downloadfilename() :- to get the filename stored in the database.
Code for Contoller

  protected ModelAndView handleRequestInternal(HttpServletRequest request,
                HttpServletResponse response) throws Exception {
            byte[] fileBytes = userService.downloadFile();
            String filename = userService.downloadFileName();

            String fileType = filename.substring(filename.indexOf(".")+1,filename.length());
            System.out.println("FILETYPE IS :>>>>>>>>>>>>>>>"+fileType);

            if (fileType.trim().equalsIgnoreCase("txt"))
            {
            response.setContentType( "text/plain" );
            }
            else if (fileType.trim().equalsIgnoreCase("doc"))
            {
            response.setContentType( "application/msword" );
            }
            else if (fileType.trim().equalsIgnoreCase("xls"))
            {
            response.setContentType( "application/vnd.ms-excel" );
            }
            else if (fileType.trim().equalsIgnoreCase("pdf"))
            {
            response.setContentType( "application/pdf" );
            }
            else if (fileType.trim().equalsIgnoreCase("ppt"))
            {
            response.setContentType( "application/ppt" );
            }
            else
            {
            response.setContentType( "application/octet-stream" );
            }

            response.setHeader("Content-Disposition","attachment; filename=\""+filename+"\"");
            response.setHeader("cache-control", "no-cache");
            response.setHeader("cache-control", "must-revalidate");

            ServletOutputStream outs = response.getOutputStream();
            outs.write(fileBytes);
            outs.flush();
            outs.close();
            return null;

        }

DAO CLASS goes like this..

public String downloadFile(){
String selectquery = "select * from upload_file where id=1";
                System.out.println("inside after query");
                ResultSet rs = stmt.executeQuery(selectquery);
                while (rs.next()) {
                    fileBytes = rs.getBytes("description");
                    fileName = rs.getString("upload_filename");
                    System.out.println("**************************************"
                            + fileName);    
                }
                return fileName;
            } catch (SQLException s) {
                System.out.println(s);
            }
            connection.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

Answer 1

You question is not really clear, but I think I know what you mean.

If a file is large (10MB) then you must specify the content length in the http header. If not the browsers will behave stange. (The exact limit 10MB is browser depended)