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 string savapath = Server.MapPath("/haha/" + path);
            //创建文件流并打开文件
            FileStream fs = new FileStream(savapath,FileMode.Open);
            //创建字节数组
            byte[] bt = new byte[(int)fs.Length];
            //流读取字节数组
            fs.Read(bt, 0, bt.Length);
            //释放资源
            fs.Close();
            Response.Charset = "UTF-8";
            Response.ContentEncoding = Encoding.Default;
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + savapath);
            Response.BinaryWrite(bt);
            Response.Flush();
            Response.End();