@RequestMapping(value = "/downloadFileFromSysDir")
  public void downloadFileFromSysDir(HttpServletResponse response) {
    String fileName = "1.txt";
    response.setHeader("content-type","application/octet-stream");
    response.setContentType("application/octet-stream");
    response.setHeader("Content-Disposition","attachment;filename=" + fileName);
    byte[] buff = new byte[1024];
    BufferedInputStream bis = null;
    OutputStream os = null;
    try {
      os = response.getOutputStream();
      bis = new BufferedInputStream(new FileInputStream(new File("D://"+ fileName)));
      int i = bis.read(buff);
      while (i != -1) {
        os.write(buff, 0, buff.length);
        os.flush();
        i = bis.read(buff);
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      if (bis != null) {
        try {
          bis.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
    System.out.println("成功下載");
  }
}