你如何获得asp:菜单以遵循Web.sitemap中提供的URL？

<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
  <siteMapNode url="~/Default.aspx" title="Home"  description="Home Page">
    <siteMapNode url="~/About.aspx" title="About Us"  description="About Us Page"/>
    <siteMapNode url="~/Contact.aspx" title="Contact Us"  description="Contact Us Page"/>
  </siteMapNode>
</siteMap>

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        Menu1.DataSourceID = "SiteMapDataSource";
        Menu1.DataBind();
    }
}