基於asp.net的Ajax 級聯下拉菜單

設計頁面：            

 <asp:DropDownList ID="DropDownList1" runat="server"></asp:DropDownList>
            <asp:DropDownList ID="DropDownList2" runat="server"></asp:DropDownList>
            <asp:DropDownList ID="DropDownList3" runat="server" OnSelectedIndexChanged="DropDownList3_SelectedIndexChanged" AutoPostBack="true"></asp:DropDownList>

            <ajaxToolkit:CascadingDropDown ID="CascadingDropDown1" Category="type" //注意這個type
            PromptText="請選擇你要查看的類別"
            ServicePath ="CascadingDropDownDemo.asmx" //獲取源數據的服務方法路徑
            ServiceMethod="GetDropDownContents" //這個是方法，在上面那個文件
            TargetControlID="DropDownList1" runat="server">
            </ajaxToolkit:CascadingDropDown>
           
           
            <ajaxToolkit:CascadingDropDown ID="CascadingDropDown2" Category="name"
            PromptText="請選擇你要查看的名稱"
            ServicePath="CascadingDropDownDemo.asmx"            

ServiceMethod="GetDropDownContents"      

TargetControlID="DropDownList2"
            ParentControlID="DropDownList1"  runat="server">
            </ajaxToolkit:CascadingDropDown>
            <ajaxToolkit:CascadingDropDown ID="CascadingDropDown3" Category="info"
            PromptText="請選擇你要查看的信息"
            ServicePath="CascadingDropDownDemo.asmx"
            ServiceMethod="GetDropDownContents"
            TargetControlID="DropDownList3"
            ParentControlID="DropDownList2" runat="server">
            </ajaxToolkit:CascadingDropDown>

 

CascadingDropDownDemo.asmx文件（是要重新建一個web服務文件）

這個實例是讀取xml文件的

using System;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Xml;
using System.Collections.Specialized;
using System.Web.Script.Services;
/// <summary>
/// CascadingDropDownDemo 的摘要說明
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

[ScriptService]//這個添加，最後那個命名空間

public class CascadingDropDownDemo : System.Web.Services.WebService {

    public CascadingDropDownDemo () {

        //如果使用設計的組件，請取消註釋以下行
        //InitializeComponent();
    }

    [WebMethod]
    public string HelloWorld() {
        return "Hello World";
    }

    private static XmlDocument _document;
    private static object _lock = new object();

    public static XmlDocument Document
    {
        get
        {
            lock (_lock)
            {
                if (_document == null)
                {
                    _document = new XmlDocument();
                    _document.Load(HttpContext.Current.Server.MapPath("~/App_Data/CascadingDropDownDemo.xml"));
                }
            }
            return _document;
        }
    }

    public static string[] Hierarchy
    {
        get { return new string[] { "type", "name" }; }
    }

    //獲取得列表數據
    [WebMethod]
    public AjaxControlToolkit.CascadingDropDownNameValue[] GetDropDownContents(string knownCategoryValues, string category)
    {
        StringDictionary knownCategoryValuesDictionary = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);
        return AjaxControlToolkit.CascadingDropDown.QuerySimpleCascadingDropDownDocument(Document, Hierarchy, knownCategoryValuesDictionary, category);
    }

 

 

   
}