更有效的文件下载功能

1.普通下载：

        //下载文件的路径
        string path=Server.MapPath("广告.jpg");
        //下载文件的名称
        string filename = "广告.jpg";
        System.IO.FileInfo toDownload = new System.IO.FileInfo(path);
        Response.Clear();
        if (System.IO.Path.GetExtension(filename) == ".jpg")
        ...{
            Response.AddHeader("Content-Disposition", "attachment;filename=NEW_" + HttpUtility.UrlEncode(toDownload.Name));
            Response.ContentType = "application/x-zip-compressed";
            Response.TransmitFile(path);
            Response.End();
        }

2.大文件分成小块下载：

        //下载文件的路径
        string path = Server.MapPath("广告.jpg");
        //下载文件的名称
        string filename = "广告.jpg";
        System.IO.FileInfo toDownload = new System.IO.FileInfo(path);

        if (toDownload.Exists == true)
        {
            const long ChunkSize = 10000;
            byte[] buffer = new byte[ChunkSize];

            Response.Clear();
            System.IO.FileStream iStream = System.IO.File.OpenRead(path);
            long dataLengthToRead = iStream.Length;
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment; filename=new_" + HttpUtility.UrlEncode(toDownload.Name));
            while (dataLengthToRead > 0 && Response.IsClientConnected)
            {
                int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));
                Response.OutputStream.Write(buffer, 0, lengthRead);
                Response.Flush();
                dataLengthToRead = dataLengthToRead - lengthRead;
            }
            Response.Close();
        }