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();
  }