下载excel文件出错

  @ResponseBody
    @RequestMapping("/download")
    public String downloadFile(HttpServletResponse response) throws IOException {


        File file = new File("D:\\iii\\11.xlsx");
        System.out.println(file.length());
        DataInputStream in = null;
        OutputStream out = null;
        response.reset();//
        try {
            response.setCharacterEncoding("UTF-8");
            response.setHeader("Content-disposition", "attachment; filename=\"" + URLEncoder.encode("11.xlsx","UTF-8"));// 设定输出文件头
            response.setContentType("application/octet-stream");// 定义输出类型
            //输入流：本地文件路径
            in = new DataInputStream(
                    new FileInputStream(new File("D:\\iii\\11.xlsx")));
            //输出流
            
            out = response.getOutputStream();
            response.getOutputStream();
            //输出文件
            int bytes = 0;
            byte[] bufferOut = new byte[1024];
            while ((bytes = in.read(bufferOut)) != -1) {
                out.write(bufferOut, 0, bytes);
            }
        }catch (Exception e){

            e.printStackTrace();

        }
     return "成功";
}

poi生成的excel文件没有问题，下载也正常，但是文件会损坏，请问是什么问题啊，大神帮忙解答一下，不胜感激

是否是编码问题