02-26C#三级省市区ajax联动控件,利用UpdatePanel，以及页面取值

第一步：设置界面

 <%@ 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> 

第二步：C#写方法函数

 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[];
         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(, 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[];
             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(, new ListItem("-请选择县区-", ""));
             DataTable dt2 = Maticsoft.DBUtility.DbHelperOra.Query("SELECT AREA FROM SY_CITYCODE Where CITY='" + SelectCity + "'").Tables[];
             ddlArea.DataTextField = "AREA";
             ddlArea.DataValueField = "AREA";
             ddlArea.DataSource = dt2;
             ddlArea.DataBind();
         }
     }
 } 

第三步：在页面中调用函数

 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);
 }