省市联动菜单(ASP.NET + XML)

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Xml;

namespace WebApplication2
{
    /**//// <summary>
    /// WebForm1 的摘要说明。
    /// </summary>
    public class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.DropDownList DropDownListProvince;
        protected System.Web.UI.WebControls.DropDownList DropDownListCity;
        protected System.Web.UI.WebControls.Label LabelMessage;

        public string City = "广州";
        
    
        private void Page_Load(object sender, System.EventArgs e)
        {
            // 在此处放置用户代码以初始化页面
            string CurrentPath = this.Server.MapPath(".");

            if (!Page.IsPostBack)
            {
                if(System.IO.File.Exists(CurrentPath + "\\Province.xml"))
                {
                    this.DropDownListProvince.Items.Clear();

                    System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
                    doc.Load(CurrentPath + "\\Province.xml");

                    XmlNodeList nodes = doc.DocumentElement.ChildNodes;

                    XmlNode node1 = doc.DocumentElement.SelectSingleNode(@"Province/City[@Name='" + this.City + "']");

                    foreach(XmlNode node in nodes)
                    {
                        this.DropDownListProvince.Items.Add(node.Attributes["Name"].Value);
                        int n = this.DropDownListProvince.Items.Count - 1;
                    
                        if(node1 != null && node == node1.ParentNode)
                            this.DropDownListProvince.SelectedIndex = n;
                    }
                    DropDownListProvince_SelectedIndexChanged(sender,e);
                }
                else
                {
                    this.LabelMessage.Text = "地市信息文件丢失！";
                }
            }
        }

        Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }
        
        /**//// <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.DropDownListProvince.SelectedIndexChanged += new System.EventHandler(this.DropDownListProvince_SelectedIndexChanged);
            this.Load += new System.EventHandler(this.Page_Load);

        }
        #endregion

        private void DropDownListProvince_SelectedIndexChanged(object sender, System.EventArgs e)
        {
            string CurrentPath = this.Server.MapPath(".");

            if(System.IO.File.Exists(CurrentPath + "\\Province.xml"))
            {
                this.DropDownListCity.Items.Clear();

                System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
                doc.Load(CurrentPath + "\\Province.xml");

                XmlNodeList nodes = doc.DocumentElement.ChildNodes[this.DropDownListProvince.SelectedIndex].ChildNodes;

                foreach(XmlNode node in nodes)
                {
                    this.DropDownListCity.Items.Add(node.Attributes["Name"].Value);
                    int n = this.DropDownListCity.Items.Count - 1;
                    if(node.Attributes["Name"].Value == this.City)
                    {
                        this.DropDownListCity.SelectedIndex = n;
                    }
                }

                if(this.DropDownListCity.SelectedIndex == -1)
                    this.DropDownListCity.SelectedIndex = 0;
            }
            else
            {
                this.LabelMessage.Text = "地市信息文件丢失！";
            }
        }

    }
}

Province.xml 文件:/Files/lmjob/Province.xml