如何在ASP.NET中的代码中动态创建文件下载链接？

<asp:Button ID="btnDownload" runat="server" Text="下载文件" OnClick="btnDownload_Click" />

protected void btnDownload_Click(object sender, EventArgs e)
{
    // 获取文件路径
    string filePath = Server.MapPath("~/文件路径/文件名.txt");

    // 设置文件名
    string fileName = "下载文件.txt";

    // 创建文件下载链接
    Response.ContentType = "application/octet-stream";
    Response.AppendHeader("Content-Disposition", "attachment; filename=" + fileName);
    Response.TransmitFile(filePath);
    Response.End();
}