code: public String save(String uploadFolder) throws ControllerException {
           String realPath = info.getRealPath(uploadFolder);
  
           fn.sanitise();
  
           String imagename = uniqueImagename(realPath, fn.fullPath());
           try {
               ImageIO.write(image, fn.extension(), new File(realPath, imagename));
               image.flush();
           } catch (IOException e) {
               throw new ControllerException(e);
           }
           return uploadFolder + File.separatorChar + imagename;
       }
docs: Saves the file on the server in the folder given
  
  @param uploadFolder
  @return The server path to the saved file.
  @throws ControllerException If anything goes wrong during write to disk.