AjaxControlToolKit 学习之：CascadingDropDown

1.CascadingDropDownNameValue：dropdownList的Text与Value 值对组 类
2.knownCategoryValues：上一级被选dropdownList的category与value 组成的字符串(数据库列名与值)
3.category：数据关联的key值（dropdownList选中项的Value）
4.ParseKnownCategoryValuesString(knownCategoryValues):将knownCategoryValues转换成tringDictionary类型
                           数据源为dataBase
  <实例源码>
  前台：

 所在区:<asp:DropDownList ID="quDrop" runat="server">
    </asp:DropDownList><br />
    &nbsp;&nbsp; 街道:<asp:DropDownList ID="streetDrop" runat="server">
    </asp:DropDownList><br />
    &nbsp;&nbsp; 大厦:<asp:DropDownList ID="houseDrop" runat="server">
    </asp:DropDownList><br />
    <ajaxToolkit:CascadingDropDown ID="CascadingDropDown1" runat="server" TargetControlID="quDrop"
     ServiceMethod="getQu" ServicePath="GetDataService.asmx" Category ="House_Qu"  LoadingText="loading" PromptText = "选择区">
    </ajaxToolkit:CascadingDropDown>
  <ajaxToolkit:CascadingDropDown ID="CascadingDropDown2" runat="server" TargetControlID="streetDrop"
     ServiceMethod="getStreet" ServicePath="GetDataService.asmx" ParentControlID="quDrop" Category="House_Street" LoadingText="loading" PromptText ="选择街道" >
    </ajaxToolkit:CascadingDropDown>
    <ajaxToolkit:CascadingDropDown ID="CascadingDropDown3" runat="server" TargetControlID="houseDrop"
     ServiceMethod="getHouseNm" ServicePath="GetDataService.asmx" ParentControlID="streetDrop" Category="House_Name" LoadingText="loading" PromptText="选择房子">
    </ajaxToolkit:CascadingDropDown>

   --------------------------------------------------------------------------------------------
 webService部分 

 

[System.Web.Script.Services.ScriptService]
public class GetDataService :WebService {
    private static readonly string connStr = ConfigurationManager.AppSettings["sqlConnctionString"].ToString();
    public GetDataService () {

        //如果使用设计的组件，请取消注释以下行 
        //InitializeComponent(); 
    }


    [WebMethod]
    public CascadingDropDownNameValue[] getQu(string knownCategoryValues, string category)  //取得区
    {
     

        List<CascadingDropDownNameValue> nameValues = new List<CascadingDropDownNameValue>();
      
        string sql = "select  distinct(House_Qu) from Houses";
        using (SqlConnection conn = new SqlConnection(connStr))
        {
            conn.Open();
            SqlCommand comm = new SqlCommand(sql, conn);
            SqlDataReader dr = comm.ExecuteReader();
            while (dr.Read())
            {
                CascadingDropDownNameValue nameValue = new CascadingDropDownNameValue();
                nameValue.name = dr.GetSqlString(0).ToString();
                nameValue.value = dr.GetSqlString(0).ToString();
                nameValues.Add(nameValue);
            }
            conn.Close();

        }
       return nameValues.ToArray();
    }
    [WebMethod]
    public CascadingDropDownNameValue[] getStreet(string knownCategoryValues, string category) //取得街道名称
    {
        System.Collections.Specialized.StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);

        if (!kv.ContainsKey("House_Qu") || string.IsNullOrEmpty(kv["House_Qu"]))
        {
            return null;
        }
        List<CascadingDropDownNameValue> nameValues = new List<CascadingDropDownNameValue>();
        string sql = "select distinct(House_Street) from Houses where House_Qu=@House_Qu";
        using (SqlConnection conn = new SqlConnection(connStr))
        {
            conn.Open();
            SqlCommand comm = new SqlCommand(sql, conn);
            comm.Parameters.Add("@House_Qu", System.Data.SqlDbType.NVarChar).Value = kv["House_Qu"];
            SqlDataReader dr = comm.ExecuteReader();
            while (dr.Read())
            {
                CascadingDropDownNameValue nameValue = new CascadingDropDownNameValue();
                nameValue.name = dr.GetSqlString(0).ToString();
                nameValue.value = dr.GetSqlString(0).ToString();
                nameValues.Add(nameValue);
            }
            conn.Close();
        }
        return nameValues.ToArray();
    }
    [WebMethod]
    public CascadingDropDownNameValue[] getHouseNm(string knownCategoryValues, string category) //取得大厦名称
    {
        System.Collections.Specialized.StringDictionary kv = CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);

        if (!kv.ContainsKey("House_Street") || string.IsNullOrEmpty(kv["House_Street"]))
        {
            return null;
        }
        List<CascadingDropDownNameValue> nameValues = new List<CascadingDropDownNameValue>();
        string sql = "select distinct(House_Name) from Houses where House_Street=@House_Street";
        using (SqlConnection conn = new SqlConnection(connStr))
        {
            conn.Open();
            SqlCommand comm = new SqlCommand(sql, conn);
            comm.Parameters.Add("@House_Street", System.Data.SqlDbType.NVarChar).Value = kv["House_Street"];
            SqlDataReader dr = comm.ExecuteReader();
            while (dr.Read())
            {
                CascadingDropDownNameValue nameValue = new CascadingDropDownNameValue();
                nameValue.name = dr.GetSqlString(0).ToString();
                nameValue.value = dr.GetSqlString(0).ToString();
                nameValues.Add(nameValue);
            }
            conn.Close();
        }
        return nameValues.ToArray();
    }

    
}

                              数据源为XML文档
webService 代码

using System;
using System.Collections.Specialized;
using System.Web;
using System.Web.Services;
using System.Xml;

/**//// <summary>
/// 
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class CarsService : WebService
{ 
    
    private static XmlDocument _document;    
    private static object _lock = new object();

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

    public static string[] Hierarchy
    {
        get { return new string[] { "make", "model" }; }
    }

    /**//// <summary>
    
    /// </summary>
    public CarsService()
    {
    }
        
    /**//// <summary>
    /// 
    
    /// 
    [WebMethod]
    public AjaxControlToolkit.CascadingDropDownNameValue[] GetDropDownContents(string knownCategoryValues, string category)
    {
        
        StringDictionary knownCategoryValuesDictionary = AjaxControlToolkit.CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues);

        
        return AjaxControlToolkit.CascadingDropDown.QuerySimpleCascadingDropDownDocument(Document, Hierarchy, knownCategoryValuesDictionary, category);
    }
}

 xml 文件

<?xml version="1.0" encoding="utf-8" ?>
<CarsService>
  <make name="Acura">
    <model name="Integra">
      <color name="Green" />
      <color name="Sea Green" />
      <color name="Pale Green" />
    </model>
    <model name="RL">
      <color name="Red" />
      <color name="Bright Red" />
    </model>
    <model name="TL">
      <color name="Teal" />
      <color name="Dark Teal" />
    </model>
  </make>
  <make name="Audi" value="Audi (value)">
    <model name="A4" value="A4 (value)">
      <color name="Azure" value="Azure (value)" />
      <color name="Light Azure" value="Light Azure (value)" />
      <color name="Dark Azure" value="Dark Azure (value)" />
    </model>
    <model name="S4" value="S4 (value)">
      <color name="Silver" value="Silver (value)" />
      <color name="Metallic" value="Metallic (value)" />
    </model>
    <model name="A6" value="A6 (value)">
      <color name="Cyan" value="Cyan (value)" />
    </model>
  </make>
  <make name="BMW" value="BMW (value)">
    <model name="3 series" value="3 series (value)">
      <color name="Blue" value="Blue (value)" />
      <color name="Sky Blue" value="Sky Blue (value)" />
      <color name="Racing Blue" value="Racing Blue (value)" />
    </model>
    <model name="5 series" value="5 series (value)">
      <color name="Yellow" value="Yellow (value)" />
      <color name="Banana" value="Banana (value)" />
    </model>
    <model name="7 series" value="7 series (value)">
      <color name="Brown" value="Brown (value)" />
    </model>
  </make>
</CarsService>