方式一：TransmitFile实现下载。将指定的文件直接写入 HTTP 响应输出流，而不在内存中缓冲该文件。

protected void Button1_Click(object sender, EventArgs e)     ...{        /**//*          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=CodeShark.zip");         string filename = Server.MapPath("DownLoad/CodeShark.zip");         Response.TransmitFile(filename);     }

方式二：WriteFile实现下载，将指定的文件直接写入 HTTP 响应输出流。注意：对大型文件使用此方法时，调用此方法可能导致异常。可以使用此方法的文件大小取决于 Web 服务器的硬件配置。

protected void Button2_Click(object sender, EventArgs e)    ...{        string fileName = "CodeShark.zip";//客户端保存的文件名    string filePath = Server.MapPath("DownLoad/CodeShark.doc");//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();    }

方式三：WriteFile分块下载

protected void Button3_Click(object sender, EventArgs e)    ...{        string fileName = "CodeShark.zip";//客户端保存的文件名    string filePath = Server.MapPath("DownLoad/CodeShark.zip");//路径   System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);        if (fileInfo.Exists == true)        ...{            const long ChunkSize = 102400;//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();        }    }

方式四：流方式下载

protected void Button4_Click(object sender, EventArgs e)    ...{        string fileName = "CodeShark.zip";//客户端保存的文件名    string filePath = Server.MapPath("DownLoad/CodeShark.zip");//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();    }