protected void Button_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=z.zip");
        string filename = Server.MapPath("DownLoad/z.zip");
        Response.TransmitFile(filename);
    }

protected void Button2_Click(object sender, EventArgs e)     {         /*          using System.IO,

  。

        */         string fileName = "asd.txt";//客户端保存的文件名          string filePath = Server.MapPath("DownLoad/aaa.txt");//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)     {         string fileName = "aaa.txt";//客户端保存的文件名          string filePath = Server.MapPath("DownLoad/aaa.txt");//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();         }     } 。

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

//---------------------------------------------------------- 。

  。

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"); 　　//'文件名称 　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'"); 　　WebForm.Response.ContentType = "Application/octet-stream"; 　　//'文件内容 　　WebForm.Response.Write(FileBody);//-----------     WebForm.Response.End(); } 。

//上面这段代码是下载一个动态产生的文本文件，若这个文件已经存在于服务器端的实体路径，则可以通过下面的函数:

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"); 　　//文件名称 　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8) +"'" ); 　　WebForm.Response.ContentType = "Application/octet-stream"; 　　//文件内容 　　WebForm.Response.Write(System.IO.File.Rea}dAllBytes(FilePath));//--------- 　　WebForm.Response.End(),

｝ 。