@RequestMapping("/download/{dt}/{filename}")
    @ResponseBody
    public String download(@PathVariable("dt") String dt,@PathVariable("filename") String filename,HttpServletResponse response) throws IOException {
        ApplicationHome appHome = new ApplicationHome(this.getClass());
        String BASE_PATH = appHome.getDir().getParentFile().getParentFile().getAbsolutePath();

        String uploadDir = BASE_PATH + "/src/main/resources/static/uploads/" + dt;
        String fileName = uploadDir + "/" + filename + ".xlsx";

        File f = new File(fileName);
        FileInputStream fis = new FileInputStream(f);
        InputStream is = new BufferedInputStream(fis);
        byte[] buffer = new byte[is.available()];
        is.read(buffer);
        is.close();

        response.reset();
        response.setCharacterEncoding("UTF-8");
//Content-Disposition的作用：告知浏览器以何种方式显示响应返回的文件，用浏览器打开还是以附件的形式下载到本地保存
//attachment表示以附件方式下载 inline表示在线打开 "Content-Disposition: inline; filename=文件名.mp3"
// filename表示文件的默认名称，因为网络传输只支持URL编码的相关支付，因此需要将文件名URL编码后进行传输,前端收到后需要反编码才能获取到真正的名称
        response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename + ".xlsx", "UTF-8"));
// 告知浏览器文件的大小
        response.addHeader("Content-Length", "" + f.length());
        OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
        response.setContentType("application/octet-stream");
        outputStream.write(buffer);
        outputStream.flush();

        return fileName;
    }