文件下载

    @GetMapping("/download")
    public void downloadFile(String fileName) throws IOException {
        BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
        File file = new File(
                System.getProperty(Constant.USER_DIR) + Constant.SPLIT
                        + Constant.UPLOAD_DIR + Constant.SPLIT + fileName);
        InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
        try (FileInputStream in = new FileInputStream(file);) {
            int len = 0;
            //创建数据缓冲区
            byte[] buffer = new byte[1024];
            //通过response对象获取outputStream流
            //将FileInputStream流写入到buffer缓冲区
            while ((len = in.read(buffer)) > 0) {
                //使用OutputStream将缓冲区的数据输出到浏览器
                out.write(buffer, 0, len);
            }
        } catch (Exception e) {
            System.out.println(e);
        }
        out.flush();
    }