springmvc模式的上传和下载实现解析

<form action="${pageContext.request.contextPath}/upload" method="post" enctype="multipart/form-data">

 @RequestMapping("/upload")  public String upload(MultipartFile file,String userName,HttpServletRequest request) throws IOException {    String filename = file.getOriginalFilename();    String suffix = filename.substring(filename.lastIndexOf("."));    if(suffix.equalsIgnoreCase(".jpg")){      String uuid = UUID.randomUUID().toString();      //FileUtils.copyInputStreamToFile(file.getInputStream(),new File("E://"+uuid+suffix));      file.transferTo(new File("D://"+System.currentTimeMillis()+suffix));//位置存储在硬盘上//      file.transferTo(new File(request.getServletContext().getRealPath("/")+"static/userImages/"+file));//      存储在项目里的目录下      request.setAttribute("result","上传成功");      return "/result.jsp";    }else{      request.setAttribute("result","上传失败");      return "/result.jsp";    }  }

@RequestMapping("/download")  public void download(String filename, HttpServletResponse response, HttpServletRequest request) throws IOException {    response.setHeader("content-disposition","attachment;filename="+filename);    ServletOutputStream outputStream = response.getOutputStream();    String path = request.getServletContext().getRealPath("images");    File file = new File(path,filename);    byte[] bytes = FileUtils.readFileToByteArray(file);    outputStream.write(bytes);    outputStream.close();  }