How to achieve multi-file upload effect in java (code example)

@ApiOperation(value = "批量上传", notes = "批量上传", httpMethod = "POST")
    @PostMapping(value = "/upload")
    public void upload(HttpServletRequest request) {
        MultipartHttpServletRequest multipartRequest=(MultipartHttpServletRequest)request;
        String savePath="E:/test/";

        //保证目录存在
        File dir = new File(savePath);
        if (!dir.isDirectory()) {
            dir.mkdirs();
        }

        Iterator<String> it = multipartRequest.getFileNames();
        while (it.hasNext()) {
            MultipartFile multipartFile = multipartRequest.getFile(it.next());
            if (multipartFile != null) {
                String originName = multipartFile.getOriginalFilename();
                int subIdx = originName.lastIndexOf(".");
                String suffix = originName.substring(subIdx);//文件后缀
                File file;
                String showName;
                while (true) {
                    showName = UUID.randomUUID().toString().replaceAll("-", "") + suffix;//文件名称
                    file = new File(savePath + showName);
                    if (!file.exists()) {
                        break;
                    }
                }
                byte[] buffer = new byte[1024];
                try (OutputStream os = new FileOutputStream(file);
                     InputStream is = multipartFile.getInputStream()){
                    while (is.read(buffer) != -1) {
                        os.write(buffer);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }