mvc3上传图片

<form id="form1" name="form1" action="CheckImg" method="post" enctype="multipart/form-data">
放一个html文件上传控件
</form>
 public ActionResult CheckImg(HttpPostedFileBase Files,string NameStr) 
        {
            if (Files == null) return "";

            string FileType = Files.FileName.Substring(Files.FileName.LastIndexOf(".") + 1);//取得类型

            if (FileType == "gif" || FileType == "GIF" || FileType == "jpg" || FileType == "JPG" || FileType == "png" || FileType == "PNG")
            {
                //新的文件名
                string ImgName = NameStr + DateTime.Now.ToString("yyyyMMddHHmmssfff")+"."+FileType;
                Files.SaveAs(Server.MapPath("/ImgUUrl/"+ImgName));
                return ImgName;
            }
            else
            {
                return "";
            }
        }