layui的文件上传跟文件保存

@*图片名称*@
      <input id="fileName" name="Photo" type="text" lay-verify="fileName"
             autocomplete="off" class="layui-input" disabled>
      @*回调的名称*@
      <input id="Photo" type="hidden" lay-verify="credentialOne"
             autocomplete="off" class="layui-input">
      <button class="layui-btn" id="ExamPhoto" type="button">
          上传图片
      </button>
      


  </div>
  <div class="layui-collapse layui-input-block" lay-accordion="" style="width: 399.5px">
      <div class="layui-colla-item">
          <h2 class="layui-colla-title">展开图片</h2>
          <div class="layui-colla-content" id="colla_img" style="">
          </div>
      </div>
  </div>

 //图片处理上产
 layui.use(['upload'], function () {
    upload.render({
        elem: '#ExamPhoto'
        , url: '/Exam/Examupload'
        , size: 5024
        , auto: false //不自动上传
        , bindAction: '#upload_img' //上传绑定到隐藏按钮
        , choose: function (obj) {
            //预读本地文件
            obj.preview(function (index, file, result) {
                $('#fileName').val(file.name);  //展示文件名
                $('#colla_img').find('img').remove();
                $('#colla_img').append('');
            })
        }
        , done: function (res) {//回调函数
            $('#Photo').val(res.data); //隐藏输入框赋值
            $('#ExxamuserAdd').click(); //上传成功后单击隐藏的提交按钮
        }
        , error: function (index, upload) {
            layer.msg('上传失败！' + index, { icon: 5 });
        }
    });
    }

string res=string.Empty;
            //获取文件
            try
            {
                HttpPostedFileBase file = Request.Files[0];
                //取到项目文件的物理路径
                string path = Server.MapPath("/images/user/") ;
                //二次拦截
                if (!Directory.Exists(path))//文件夹不存在    
                {
                    Directory.CreateDirectory(path);//创建文件夹    

                }
                path += file.FileName;
                if (file.FileName.EndsWith("jpg") || file.FileName.EndsWith("png") || file.FileName.EndsWith("gif"))
                {
                    file.SaveAs(path);//文件进行保存
                    res = file.FileName;
                }
            }
            catch (Exception)
            {
                res = "NO";
            }
            

            var json = new
            {
                cod = 0,
                data = res
            };


            return Json(json, JsonRequestBehavior.AllowGet);