Get ancestors list in an XML document

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using System.Xml;

namespace ReadXmlDemo
{
    /**//// <summary>
    /// Form1 的摘要说明。
    /// </summary>
    public class Form1 : Form
    {
        private Button button1;
        private Container components = null;

        public static void Main()
        {
            Application.Run(new Form1());
        }

        public Form1()
        {
            InitializeComponent();
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing) {
                if (components != null) {
                    components.Dispose();
                }
            }
            base.Dispose(disposing);
        }

        Windows 窗体设计器生成的代码#region Windows 窗体设计器生成的代码

        /**//// <summary>
        /// 设计器支持所需的方法 - 不要使用代码编辑器修改
        /// 此方法的内容。
        /// </summary>
        private void InitializeComponent()
        {
            this.button1 = new Button();
            this.SuspendLayout();
            // 
            // button1
            // 
            this.button1.Location = new Point(176, 48);
            this.button1.Name = "button1";
            this.button1.TabIndex = 0;
            this.button1.Text = "button1";
            this.button1.Click += new EventHandler(this.button1_Click);
            // 
            // Form1
            // 
            this.AutoScaleBaseSize = new Size(6, 14);
            this.ClientSize = new Size(292, 273);
            this.Controls.Add(this.button1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);

        }

        #endregion

        private void button1_Click(object sender, EventArgs e)
        {
            Setup();

            string url = "/pmanager/scm/frmscmindex.aspx";
            string param = "projectid";

            XmlNode[] ancestors = GetAncestorNodeList(url, param);

            // test results
            if (ancestors != null) {
                foreach (XmlNode node in ancestors)
                    MessageBox.Show(node.OuterXml);
            }
        }

        private XmlDocument doc;

        /**//// <summary>
        /// 加载 Xml 文档
        /// </summary>
        private void Setup()
        {
            doc = new XmlDocument();
            try {
                doc.Load(Application.StartupPath + "//nav.xml");
            }
            catch {
                throw new Exception("Xml 文件加载失败。");
            }
        }

        /**//// <summary>
        /// 得到指定节点的祖先节点的数组（强类型）
        /// </summary>
        /// <param name="url"></param>
        /// <param name="param"></param>
        /// <returns></returns>
        private XmlNode[] GetAncestorNodeList(string url, string param)
        {
            XmlNode targetNode = doc.SelectSingleNode("//siteMapNode[@url='" + url + "' and @param='" + param + "']");
            if (targetNode == null)
                return null;

            ArrayList alAncestors = new ArrayList();

            for (XmlNode node = targetNode.ParentNode;
                node != null && node != doc.DocumentElement;
                node = node.ParentNode) {
                    alAncestors.Add(node);
            }
            alAncestors.Reverse();

            XmlNode[] nodeList = (XmlNode[]) alAncestors.ToArray(typeof (XmlNode));

            return nodeList;
        }
    }
}