一、//TransmitFile實現下載 
    protected void Button1_Click(object sender, EventArgs e)
    {
        /* 
        微軟為Response物件提供了一個新的方法TransmitFile來解決使用Response.BinaryWrite 
        下載超過400mb的檔案時導致Aspnet_wp.exe程序回收而無法成功下載的問題。 
        程式碼如下： 
        */ 
        Response.ContentType = "application/x-zip-compressed";
        Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");
        string filename = Server.MapPath("DownLoad/z.zip");
        Response.TransmitFile(filename);
    }

二、//WriteFile實現下載 
    protected void Button2_Click(object sender, EventArgs e)
    {
        /* 
        using System.IO;

        */
        string fileName = "asd.txt";//客戶端儲存的檔名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

        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();
    }

三、   //WriteFile分塊下載 
    protected void Button3_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客戶端儲存的檔名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

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

        if (fileInfo.Exists == true)
        {
            const long ChunkSize = 102400;//100K 每次讀取檔案，只讀取100K，這樣可以緩解伺服器的壓力 
            byte[] buffer = new byte[ChunkSize];

            Response.Clear();
            System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
            long dataLengthToRead = iStream.Length;//獲取下載的檔案總大小 
            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));//讀取的大小 
                Response.OutputStream.Write(buffer, 0, lengthRead);
                Response.Flush();
                dataLengthToRead = dataLengthToRead - lengthRead;
            }
            Response.Close();
        }
    }

四、//流方式下載 
    protected void Button4_Click(object sender, EventArgs e)
    {
        string fileName = "aaa.txt";//客戶端儲存的檔名 
        string filePath = Server.MapPath("DownLoad/aaa.txt");//路徑

        //以字元流的形式下載檔案 
        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";
        //通知瀏覽器下載檔案而不是開啟 
        Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
        Response.BinaryWrite(bytes);
        Response.Flush();
        Response.End();
    }

//----------------------------------------------------------

public void DownloadFile( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FileBody )
{

　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
　　WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//'檔名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'");
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//'檔案內容
　　WebForm.Response.Write(FileBody);//-----------
    WebForm.Response.End();
}

//上面這段程式碼是下載一個動態產生的文字檔案，若這個檔案已經存在於伺服器端的實體路徑，則可以通過下面的函式：

public void DownloadFileByFilePath( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FilePath )
{
　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
    WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//檔名稱
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) +"'" );
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//檔案內容
　　WebForm.Response.Write(System.IO.File.Rea}dAllBytes(FilePath));//---------
　　WebForm.Response.End();