asp.net 点击按钮以另存为方式保存文件急等

我需要实现点击按钮打开一个另存为的选择路径的对话框

代码如下

// 要下载的文件全名
            string FullFileName = Server.MapPath(@"/Excel/myExcel.xlsx"); //FileName--要下载的文件名
                                                                          // 下载文件
            System.IO.FileInfo DownloadFile = new System.IO.FileInfo(FullFileName);
            if (DownloadFile.Exists)
            {
                Response.Clear();
                Response.ClearHeaders();
                Response.Buffer = false;
                // 设置内容类型 (https://blog.csdn.net/qwlovedzm/article/details/7247803)
                // 链接内有文件后缀匹配赋值给ContentType
                Response.ContentType = "application/vnd.ms-excel";
                Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(DownloadFile.Name, System.Text.Encoding.ASCII));
                Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
                Response.WriteFile(DownloadFile.FullName);
                Response.Flush();
                Response.End();
            }
            else
            {
                Response.Write("<scrpit>alert('导出失败')</scrpit>");
            }

我这个代码是可以保存的，但是并不能够打开另存为的对话框

另存为是浏览器控制的，如浏览器设置过默认保存路径是直接保存到默认路径。除非设置成每次都询问用户保存的位置才会弹出选择对话框