下载的四种方法

 protected void Button1_Click(object sender, EventArgs e)        {            //TransmitFile实现下载

            /**/            /*             微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite             下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。             代码如下：            */

            Response.ContentType = "application/x-zip-compressed";            Response.AddHeader("Content-Disposition", "attachment;filename=keji.rar");            string filename = Server.MapPath("keji.rar");            Response.TransmitFile(filename);            Response.Write("<script language=/"javascript/" type=/"text/javascript/">");            Response.Write("alert(/"下载成功/");");            Response.Write("window.location.href=/"C_SC.aspx/";");            Response.Write("</script>");        }

        protected void Button2_Click(object sender, EventArgs e)        {

            //WriteFile实现下载            string fileName = "ceshi.rar";//客户端保存的文件名            string filePath = Server.MapPath("keji.rar");//路径

            FileInfo fileInfo = new FileInfo(filePath);            Response.Clear();            Response.ClearContent();            Response.ClearHeaders();            Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);            Response.AddHeader("Content-Length", fileInfo.Length.ToString());            Response.AddHeader("Content-Transfer-Encoding", "binary");            Response.ContentType = "application/octet-stream";            Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");            Response.WriteFile(fileInfo.FullName);            Response.Flush();            Response.End();        }

        protected void Button3_Click(object sender, EventArgs e)        {            //WriteFile分块下载

            string fileName = "GhostXP.iso";//客户端保存的文件名            string filePath = Server.MapPath("GhostXP7.7.iso");//路径

            System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);

            if (fileInfo.Exists == true)            {                const long ChunkSize = 409600;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力                byte[] buffer = new byte[ChunkSize];

                Response.Clear();                System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);                long dataLengthToRead = iStream.Length;//获取下载的文件总大小                Response.ContentType = "application/octet-stream";                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));                while (dataLengthToRead > 0 && Response.IsClientConnected)                {                    int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小                    Response.OutputStream.Write(buffer, 0, lengthRead);                    Response.Flush();                    dataLengthToRead = dataLengthToRead - lengthRead;                }                Response.Close();            }        }

        //字符流方式下载文件        protected void Button4_Click(object sender, EventArgs e)        {            string fileName = "ce2.rar";//客户端保存的文件名            string filePath = Server.MapPath("keji.rar");//路径

            //以字符流的形式下载文件            FileStream fs = new FileStream(filePath, FileMode.Open);            byte[] bytes = new byte[(int)fs.Length];            fs.Read(bytes, 0, bytes.Length);            fs.Close();            Response.ContentType = "application/octet-stream";            //通知浏览器下载文件而不是打开            Response.AddHeader("Content-Disposition", "attachment;   filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));            Response.BinaryWrite(bytes);            Response.Flush();            Response.End();        }