AJAX无刷新实现三级联动并获取DropDownList的值的方法

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="AdvancedSearch.aspx.cs"
    Inherits="SchoolCrm.Web.AdvancedSearch" MasterPageFile="~/FrontDeskShow.Master"
    EnableEventValidation="false" %>

<%@ Register Assembly="SchoolCrm.Web" Namespace="SchoolCrm.Web.Contorls" TagPrefix="cc1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server">
    <style type="text/css">
        #tablestyle
        {
             100%;
            border-style: solid;
        }
        #tdTitle
        {
            text-align: center;
            background-color: #F0F7F9;
        }
        #tabletd
        {
            background-color: White;
            border-bottom- 2px;
        }
        #ProfessionName
        {
             134px;
        }
    </style>

    <script type="text/javascript">
  
        //省市级联 --省份
        $(function() {

            $("#ctl00_Content_DropProvinceList1").focus(function() {
                var text_val = $(this).val();
                if (text_val == this.defaultValue) {
                    $(this).val("");
                }
            }).blur(function() {
                var text_val = $(this).val();
                if (text_val == "") {
                    $(this).val(this.defaultValue);
                } else {
                    var name = $(this).val();

                    $.post("AjaxToprofessionaByWhere.aspx", { ProvinceNameId: encodeURI(name) }, function(data, success) {
                        if (success == "success") {
                            $("#ctl00_Content_DropCityList1").html(data);
                        }
                    });
                }
            });
        })


        function getData() {
          
            $("#ctl00_Content_SchoolHidden").val(str1);
            //城市
            var str1 = $("#ctl00_Content_DropCityList1 :selected").val();
            $("#ctl00_Content_CityHidden").val(str1);
          
        }

    </script>

</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="Content" runat="server">
    <div>
        <table id="tablestyle" border="0" cellpadding="5" cellspacing="1" bgcolor="#B5D6E7">
            <tr>
                <td id="tdTitle">
                    所属地
                </td>
                <td id="tabletd">
                    <asp:DropDownList ID="DropCountryList1" runat="server" Height="23px" Width="100px"
                        Enabled="False">
                    </asp:DropDownList>
                    <cc1:DropProvinceList ID="DropProvinceList1" runat="server" Height="23px" Width="100px">
                        <asp:ListItem Value="0">请选择</asp:ListItem>
                    </cc1:DropProvinceList>
                    <cc1:DropCityList ID="DropCityList1" runat="server" Height="23px" Width="100px">
                        <asp:ListItem Value="0">请选择</asp:ListItem>
                    </cc1:DropCityList>
                </td>
            </tr>
            <tr>
                <td id="tdTitle">
                </td>
                <td id="tabletd">
                    <asp:Button ID="Search" runat="server" Text="搜索" OnClick="Search_Click" OnClientClick="return getData()" />
                    &nbsp;&nbsp;&nbsp;
                    <asp:Button ID="btnCancel" runat="server" Text="取消" OnClick="btnCancel_Click" />
                </td>
            </tr>
        </table>
    </div>
    <input type="hidden" id="profeeHidden" runat="server" />
    <input type="hidden" id="SchoolHidden" runat="server" />
    <input type="hidden" id="CityHidden" runat="server" />
    <input type="hidden" id="DergeeHidden" runat="server" />
</asp:Content>

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 System.Collections.Generic;
using System.Text;
using System.Web.Script.Serialization;


namespace SchoolCrm.Web
{
    public partial class AjaxToprofessionaByWhere : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                if (Request["ProvinceNameId"] != null)
                {
                    ProvinceName(Request["ProvinceNameId"].ToString());
                }
            }
        }

        BLL.Country country = new SchoolCrm.BLL.Country();
        BLL.Province province = new SchoolCrm.BLL.Province();
        BLL.City city = new SchoolCrm.BLL.City();

        /// <summary>
        /// 省市级联  --省份
        /// </summary>
        /// <param name="ProfessionalName"></param>
        private void ProvinceName(string ProvinceNameId)
        {
            string url = Server.UrlDecode(ProvinceNameId);
            List<Model.City> list = city.SelectCityByProvinceIdAndCountryId("1", url);
            // List<Model.Province> list = province.SelectProvinceByCountryId(url);
            StringBuilder str = new StringBuilder();
            str.AppendFormat("<option value='{0}'>{1}</option>", 0, "请选择");
            foreach (Model.City item in list)
            {
                str.AppendFormat("<option value='{0}'>{1}</option>", item.CityId, item.ChineseName);
            }
            Response.Write(str.ToString());
            Response.End();



        }

    }
}