C#三级省市区ajax联动控件,利用UpdatePanel，以及页面取值

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="PCAControl.ascx.cs" Inherits="PCAControl" %>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <asp:DropDownList ID="ddlProvice" runat="server" AppendDataBoundItems="true" AutoPostBack="true"
            OnSelectedIndexChanged="ddlProvice_SelectedIndexChanged">
            <asp:ListItem Text="-请选择省份-" Value=""></asp:ListItem>
        </asp:DropDownList>
        <asp:DropDownList ID="ddlCity" runat="server" AutoPostBack="true"
            onselectedindexchanged="ddlCity_SelectedIndexChanged">
            <asp:ListItem Text="-请选择城市-" Value=""></asp:ListItem>
        </asp:DropDownList>
        <asp:DropDownList ID="ddlArea" runat="server">
            <asp:ListItem Text="-请选择县区-" Value=""></asp:ListItem>
        </asp:DropDownList>
    </ContentTemplate>
</asp:UpdatePanel>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class PCAControl : System.Web.UI.UserControl
{

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindProvince();
        }
    }

    //加载省份
    protected void BindProvince()
    {
        DataTable dt = Maticsoft.DBUtility.DbHelperOra.Query("SELECT DISTINCT PROVINCE FROM SY_CITYCODE  GROUP   BY PROVINCE").Tables[0];
        ddlProvice.DataTextField = "PROVINCE";
        ddlProvice.DataValueField = "PROVINCE";
        ddlProvice.DataSource = dt;
        ddlProvice.DataBind();
    }

    //加载城市
    protected void ddlProvice_SelectedIndexChanged(object sender, EventArgs e)
    {
        string SelectPro = ddlProvice.SelectedValue;
        if (!string.IsNullOrEmpty(SelectPro))
        {
            ddlCity.Items.Clear();
            ddlCity.AppendDataBoundItems = true;
            ddlCity.Items.Insert(0, new ListItem("-请选择城市-", ""));
            DataTable dt1 = Maticsoft.DBUtility.DbHelperOra.Query("SELECT CITY FROM SY_CITYCODE Where PROVINCE='" + SelectPro + "'  Group By City").Tables[0];
            ddlCity.DataTextField = "CITY";
            ddlCity.DataValueField = "CITY";
            ddlCity.DataSource = dt1;
            ddlCity.DataBind();
        }
    }

    //加载县区
    protected void ddlCity_SelectedIndexChanged(object sender, EventArgs e)
    {
        string SelectCity = ddlCity.SelectedValue;
        if (!string.IsNullOrEmpty(SelectCity))
        {
            ddlArea.Items.Clear();
            ddlArea.AppendDataBoundItems = true;
            ddlArea.Items.Insert(0, new ListItem("-请选择县区-", ""));
            DataTable dt2 = Maticsoft.DBUtility.DbHelperOra.Query("SELECT AREA FROM SY_CITYCODE Where CITY='" + SelectCity + "'").Tables[0];
            ddlArea.DataTextField = "AREA";
            ddlArea.DataValueField = "AREA";
            ddlArea.DataSource = dt2;
            ddlArea.DataBind();
        }
    }
}

调用页面取值

    protected void Button1_Click(object sender, EventArgs e)
    {
        string SelectedProv = ((DropDownList)PCAControl1.FindControl("ddlProvice")).SelectedValue;
        string SelectedCity = ((DropDownList)PCAControl1.FindControl("ddlCity")).SelectedValue;
        string SelectedArea = ((DropDownList)PCAControl1.FindControl("ddlArea")).SelectedValue;
        MSCL.JsHelper.Alert(SelectedProv + "-" + SelectedCity + "-" + SelectedArea, Page);
    }