修改XML结点

void Update()
    {
        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.Load(Server.MapPath(datafile));

        XmlNodeList nodeList = xmlDoc.SelectSingleNode("Advertisements").ChildNodes;//获取Advertisements节点的所有子节点

        foreach (XmlNode xn in nodeList)//遍历所有子节点
        {
            XmlElement xe = (XmlElement)xn;//将子节点类型转换为XmlElement类型
            if (xe.GetAttribute("genre") == Request.QueryString["ID"].ToString())//如果genre属性值为“张三”
            {
                xe.SetAttribute("genre", this.TextBox1.Text);//则修改该属性为“update张三”

                XmlNodeList nls = xe.ChildNodes;//继续获取xe子节点的所有子节点
                foreach (XmlNode xn1 in nls)//遍历
                {
                    XmlElement xe2 = (XmlElement)xn1;//转换类型
                    if (xe2.Name == "ImageUrl")//如果找到
                    {
                        xe2.InnerText = this.TextBox1.Text;//则修改
                    }
                }
            }
        }
        xmlDoc.Save(Server.MapPath(datafile));

}