个人总结——dropdownlist联动控件

要形成如下的联动：选择省——下个dropdownlist出现本省所有的市——出现县——依次类推，定义相关属性（隐藏，赋值等）

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using BLLibrary;
using Model;
using System.Collections.Generic;
using AjaxControlToolkit;
namespace sydweb.controls
{
    public partial class AdminAreaNew : System.Web.UI.UserControl
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                
            }
        }
        #region 数据绑定
        public void ProvinceBind()
        {
            List<ListItem> returnvalue = new List<ListItem>();
            returnvalue.Add(new ListItem("河北省", "13"));
            ddlprovince.DataSource = returnvalue;
            ddlprovince.DataBind();
        }

        public void CityBind()
        {
            ddlcity.Items.Clear();
            List<ListItem> returnvalue1 = new List<ListItem>();
            //returnvalue1 = firmcodesupport.region2.getarrarybydwbm("13");
            returnvalue1 = classes.gxmc.getarrarybydwbm("13", 4);
            //returnvalue1.Insert(0, new ListItem("请选择", "0"));
            ddlcity.DataSource = returnvalue1;
            ddlcity.DataBind();
            ddlcity.Items.Insert(0, new ListItem("请选择", "0"));
        }

        public void CountyBind()
        {
            ddlcounty.Items.Clear();
            List<ListItem> returnvalue2 = new List<ListItem>();
            //returnvalue2 = firmcodesupport.region2.getarrarybydwbm(ddlcity.SelectedValue);
            returnvalue2 = classes.gxmc.getarrarybydwbm(ddlcity.SelectedValue, 6);
            //returnvalue2.Insert(0, new ListItem("请选择", "0"));
            ddlcounty.DataSource = returnvalue2;
            ddlcounty.DataBind();
            ddlcounty.Items.Insert(0, new ListItem("请选择", "0"));

        }
        public void TownBind()
        {
            ddltown.Items.Clear();
            List<ListItem> returnvalue3 = new List<ListItem>();
            //returnvalue3 = firmcodesupport.region2.getarrarybydwbm(ddlcounty.SelectedValue);
            returnvalue3 = classes.gxmc.getarrarybydwbm(ddlcounty.SelectedValue, 9);
            //returnvalue3.Insert(0, new ListItem("请选择", "0"));
            ddltown.DataSource = returnvalue3;
            ddltown.DataBind();
            ddltown.Items.Insert(0, new ListItem("请选择", "0"));

        }

        #endregion
        #region 选择
        /// <summary>
        /// 地区，取、设置，直接使用地域代码来设置
        /// add by lww @ 20090504
        /// </summary>
        public string area
        {
            get
            {
                if (ddltown.SelectedIndex != 0) return ddltown.SelectedValue;
                if (ddlcounty.SelectedIndex != 0) return ddlcounty.SelectedValue;
                if (ddlcity.SelectedIndex != 0) return ddlcity.SelectedValue;
                if (ddlprovince.SelectedIndex != 0) return ddlprovince.SelectedValue;
                return null;
            }
            set
            {
                string area = value;
                if (area.Length >= 2) Province = value.Substring(0, 2);
                if (area.Length >= 4) City = value.Substring(0, 4);
                if (area.Length >= 6) County = value.Substring(0, 6);
                if (area.Length >= 9) Town = value.Substring(0, 9);

            }
        }


        /// <summary>
        /// 省
        /// </summary>
        public string Province
        {
            get { return ddlprovince.SelectedValue; }
            set
            {
                ProvinceBind();
                ddlprovince.SelectedValue = value;
                CityBind();
            }
        }
        /// <summary>
        /// 市
        /// </summary>
        public string City
        {
            get { return ddlcity.SelectedValue; }
            set
            {
                ddlcity.SelectedValue = value;
                CountyBind();
            }
        }
        /// <summary>
        /// 县，区
        /// </summary>
        public string County
        {
            get { return ddlcounty.SelectedValue; }
            set
            {
                ddlcounty.SelectedValue = value;
                TownBind();
            }
        }
        //乡镇
        public string Town
        {
            get { return ddltown.SelectedValue; }
            set
            {
                ddltown.SelectedValue = value;
            }
        }

        #endregion
        #region 是否可用
        /// <summary>
        /// 允许选择省
        /// </summary>
        public bool ProvinceEnabled
        {
            get { return ddlprovince.Enabled; }
            set
            {
                ddlprovince.Enabled = value;
            }
        }

        /// <summary>
        /// 允许选择市
        /// </summary>
        public bool CityEnabled
        {
            get { return ddlcity.Enabled; }
            set
            {
                ddlcity.Enabled = value;
            }
        }
        /// <summary>
        /// 允许选择县区
        /// </summary>
        public bool CountyEnabled
        {
            get { return ddlcounty.Enabled; }
            set
            {
                ddlcounty.Enabled = value;
            }
        }
        /// <summary>
        /// 允许选择乡镇
        /// </summary>
        public bool TownEnabled
        {
            get { return ddltown.Enabled; }
            set
            {
                ddltown.Enabled = value;
            }
        }


        #endregion
        #region 是否显示
        /// <summary>
        /// 省级是否显示
        /// </summary>
        public bool ProviceVisible
        {
            get
            {
                return ddlprovince.Visible;
            }
            set
            {
                ddlprovince.Visible = value;
                lbprovince.Visible = value;
            }
        }
        /// <summary>
        /// 市级是否显示
        /// </summary>
        public bool CityVisible
        {
            get
            {
                return ddlcity.Visible;
            }
            set
            {
                ddlcity.Visible = value;
                lbcity.Visible = value;
            }
        }
        /// <summary>
        /// 县级是否显示
        /// </summary>
        public bool CountyVisible
        {
            get
            {
                return ddlcounty.Visible;
            }
            set
            {
                ddlcounty.Visible = value;
                lbcounty.Visible = value;
            }
        }
        /// <summary>
        /// 乡级是否显示
        /// </summary>
        public bool TownVisible
        {
            get
            {
                return ddltown.Visible;
            }
            set
            {
                ddltown.Visible = value;
                lbtown.Visible = value;
            }
        }
        #endregion
        #region 联动
        protected void ddlprovince_SelectedIndexChanged(object sender, EventArgs e)
        {
            //List<ListItem> returnvalue = new List<ListItem>();
            //returnvalue.Add(new ListItem("河北省", "13"));
            //ddlprovince.DataSource = returnvalue.ToArray();
            //ddlprovince.DataBind();
        }

        protected void ddlcity_SelectedIndexChanged(object sender, EventArgs e)
        {
            List<ListItem> returnvalue5 = new List<ListItem>();
            if (ddlcity.SelectedIndex == 0)
            {
                ddlcounty.Items.Clear();
                ddlcounty.Items.Insert(0, new ListItem("请选择", "0"));
                ddlcounty.SelectedIndex = -1;
                ddlcounty.Enabled = false;
                ddltown.SelectedIndex = -1;
                ddltown.Enabled = false;
                ddltown.Items.Clear();
                ddltown.Items.Insert(0, new ListItem("请选择", "0"));


            }
            else
            {
                ddlcounty.Items.Clear();
                //returnvalue5 = firmcodesupport.region2.getarrarybydwbm(ddlcity.SelectedItem.Value);
                returnvalue5 = classes.gxmc.getarrarybydwbm(ddlcity.SelectedItem.Value, 6);

                ddlcounty.DataSource = returnvalue5;
                ddlcounty.DataBind();
                ddlcounty.Items.Insert(0, new ListItem("请选择", "0"));
                ddlcounty.Enabled = true;
                ddltown.Items.Clear();
                ddltown.Items.Insert(0, new ListItem("请选择", "0"));
            }


        }

        protected void ddlcounty_SelectedIndexChanged(object sender, EventArgs e)
        {
            List<ListItem> returnvalue6 = new List<ListItem>();

            if (ddlcounty.SelectedIndex == 0)
            {
                ddltown.Items.Clear();
                ddltown.Items.Insert(0, new ListItem("请选择", "0"));

                ddltown.SelectedIndex = -1;
                ddltown.Enabled = false;

            }
            else
            {
                ddltown.Items.Clear();
                //returnvalue6 = firmcodesupport.region2.getarrarybydwbm(ddlcounty.SelectedItem.Value);
                returnvalue6 = classes.gxmc.getarrarybydwbm(ddlcounty.SelectedItem.Value, 9);
                ddltown.DataSource = returnvalue6;
                ddltown.DataBind();
                ddltown.Items.Insert(0, new ListItem("请选择", "0"));
                ddltown.Enabled = true;
            }


        }
        #endregion
        #region 访问当前的选择zbx
        public ArrayList currentselect
        {
            get
            {
                ArrayList bakal = new ArrayList();
                bakal.Add(ddlprovince.SelectedValue);
                bakal.Add(ddlcity.SelectedValue);
                bakal.Add(ddlcounty.SelectedValue);
                bakal.Add(ddltown.SelectedValue);
                return bakal;
            }
        }
        #endregion
    }
}