ASP.NET下载文件(弹出打开保存文件对话框)

//fileURL为带路径的文件全名

System.IO.FileInfo fileInfo = new System.IO.FileInfo(fileURL);
            Response.Clear();
            Response.AddHeader("content-disposition","attachment;filename="+Server.UrlEncode(fileInfo.Name.ToString()));
            Response.AddHeader("content-length",fileInfo.Length.ToString());
            Response.ContentType = "application/octet-stream";
            Response.ContentEncoding = System.Text.Encoding.Default;
            Response.WriteFile(fileURL); 

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Response.ContentType = "image/jpeg";
Response.AppendHeader("Content-Disposition","attachment; filename=SailBig.jpg");
Response.TransmitFile( Server.MapPath("~/images/sailbig.jpg") );
Response.End();