文件myfile=NULL给人一个错误tthat说可以不declaire39＃静态类型的变量;System.IO.File＃39;请帮我OU

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.IO;

using System.Data;

using System.Data.SqlClient;

using System.Text;

using System.Configuration;

using System.Data.Sql;

using System.Media;

 



 

namespace PDF_Files

{

    public partial class DownloadFile : System.Web.UI.Page

    {

 

        File myFile = null;

        protected void Page_Load(object sender, EventArgs e)

        {

 

            Response.ContentType = "application/x-uknown";

            Response.AppendHeader("Content - Disposiotion", "atachment;filename=\"" + myFile.OriginalName + "\"");

            if (myFile != null)

            {

                Response.BinaryWrite(myFile.FileData);

            }

            else

            {

                Response.WriteFile(Path.Combine(AppConfiguration.UploadFolder, myFile.FileUrl));

 

            }

        }

    }

}

File Class Sample