代码如下：

      byte[] buffer=(byte[])ds.Tables[0].Rows[0]["Content"];
      //buffer数组为要读取的文件流
       Response.Clear();
       Response.AddHeader("Content-Disposition","attachment; filename="+ds.Tables[0].Rows[0]   ["FName"].ToString());
     //ds.Tables[0].Rows[0]["FName"].ToString()为要下载的文件名
       Response.ContentType="application/x-msdownload";

       Response.BinaryWrite(buffer);
       Response.End();