base64文件上传 java.io.FileNotFoundException 拒绝访问

file:
   accessPath: /file/**  #访问文件前缀
   uploadFolder: d://uploadFiles/  #上传文件存放路径
/**
     *  移动端上传图片
     *  base64字符串转化成图片
     */
    @RequestMapping(value = "uploadImage", method = RequestMethod.POST)
    public ApiResult<String> uploadImage(@RequestBody String requestVO) throws Exception {
        ApiResult<String> result = new ApiResult<String>();
        String resultPath = "";
//替换掉base64头部
        String imgStr = requestVO.replaceAll("data:image/png;base64,","");
        // Base64解码
        byte[] b = Base64.decode(imgStr);
        for (int i = 0; i < b.length; ++i) {
            if (b[i] < 0) {// 调整异常数据
                b[i] += 256;
            }
        }
        String fileName = FileUtil.getFileName(".jpg");
        File tagetFile = new File(uploadFolder+fileName);
        if (!tagetFile.exists()) {
            try
            {
                tagetFile.getParentFile().mkdirs();  // 先创建目录
                tagetFile.createNewFile();  //创建文件
            }
            catch (Exception ex)
            {
                throw new RuntimeException("The direction creat fail");
            }
        }
        // 生成jpeg图片
        FileOutputStream fout = new FileOutputStream(tagetFile);
        fout.write(b);
        fout.flush();
        fout.close();
 
        resultPath = accessPath.substring(0, accessPath.lastIndexOf('/') + 1) + fileName;
        result.setData(resultPath);
        result.setCodeToSuccessed();
        return result;
    }