<asp:ScriptManager ID="ScriptManager1" runat="server">

    </asp:ScriptManager>

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">

        <ContentTemplate>

            <asp:DropDownList ID="ddl_Province" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddl_Province_SelectedIndexChanged">

            </asp:DropDownList>

            <asp:DropDownList ID="ddl_City" runat="server" AutoPostBack="True" OnSelectedIndexChanged="ddl_City_SelectedIndexChanged">

            </asp:DropDownList>

            <asp:DropDownList ID="ddl_Area" runat="server">

            </asp:DropDownList>

        </ContentTemplate>

    </asp:UpdatePanel>

protected void Page_Load(object sender, EventArgs e)

        {

            if (!Page.IsPostBack)

            {

                BindProvince();

                BindCity(ddl_Province.SelectedItem.Value);

                BindArea(ddl_City.SelectedItem.Value);

            }

        }

        #region 三级省市区联动xml

        private void BindProvince()

        {

            XmlDocument xmlDoc = new XmlDocument();

            xmlDoc.Load(Server.MapPath("ChinaArea.xml"));

            XmlNodeList nodelist = xmlDoc.SelectNodes("area/province[@provinceID]");

            ListItem li = null;

            foreach (XmlNode myNode in nodelist)

            {

                li = new ListItem();

                li.Value = myNode.Attributes["provinceID"].Value;

                li.Text = myNode.Attributes["province"].Value;

                this.ddl_Province.Items.Add(li);

            }

        }

        private void BindCity(string code)

        {

            XmlDocument xmlDoc = new XmlDocument();

            xmlDoc.Load(Server.MapPath("ChinaArea.xml"));

            XmlNodeList nodelist = xmlDoc.SelectNodes(string.Format("area/province[@provinceID={0}]/City",code));

            ListItem li = null;

            foreach (XmlNode myNode in nodelist)

            {

                li = new ListItem();

                li.Value = myNode.Attributes["CityID"].Value;

                li.Text = myNode.Attributes["City"].Value;

                this.ddl_City.Items.Add(li);

            }

        }

        private void BindArea(string code)

        {

            XmlDocument xmlDoc = new XmlDocument();

            xmlDoc.Load(Server.MapPath("ChinaArea.xml"));

            XmlNodeList nodelist = xmlDoc.SelectNodes(string.Format("area/province/City[@CityID={0}]/Piecearea",code));

            ListItem li = null;

            foreach (XmlNode myNode in nodelist)

            {

                li = new ListItem();

                li.Value = myNode.Attributes["PieceareaID"].Value;

                li.Text = myNode.Attributes["Piecearea"].Value;

                this.ddl_Area.Items.Add(li);

            }

        }

        protected void ddl_City_SelectedIndexChanged(object sender, EventArgs e)

        {

            ddl_Area.Items.Clear();

            BindArea(ddl_City.SelectedItem.Value);

        }

        protected void ddl_Province_SelectedIndexChanged(object sender, EventArgs e)

        {

            ddl_City.Items.Clear();

            ddl_Area.Items.Clear();

            BindCity(ddl_Province.SelectedItem.Value);

            BindArea(ddl_City.SelectedItem.Value);

        }

        #endregion