本文主要列举了省市三级联动的DropDownList+Ajax的三种框架(aspnet/Jquery/ExtJs)示例。前段时间需要作一个的Web前端应用，需要用多个框架，一个典型的应用场景是省市三级联动，基于此应用，特将三种主要的ajax框架略作整理，方便有需要的朋友查阅。

在示例之前，我们先设置一个演示数据源，新建一个项目，项目结构如图：

主要文件如下：

AreaModel.cs:

using System;

using System.Collections.Generic;

namespace Downmoon.Framework.Model

{

#region PopularArea

public class Area

{

private string m_Area_ID;

///

/// 地区编号

///

public string Area_ID

{

get { return m_Area_ID; }

set { m_Area_ID = value; }

}

private string m_Area_Name;

///

/// 地区名称

///

public string Area_Name

{

get { return m_Area_Name; }

set { m_Area_Name = value; }

}

private double m_Area_Order;

///

/// 排序

///

public double Area_Order

{

get { return m_Area_Order; }

set { m_Area_Order = value; }

}

private int m_Area_Layer;

///

/// 层级

///

public int Area_Layer

{

get { return m_Area_Layer; }

set { m_Area_Layer = value; }

}

private string m_Area_FatherID;

///

/// 父级ID

///

public string Area_FatherID

{

get { return m_Area_FatherID; }

set { m_Area_FatherID = value; }

}

public Area() { }

public Area(string id, string name, double order, int layer, string father)

{

this.Area_ID = id;

this.Area_Name = name;

this.m_Area_Order = order;

this.m_Area_Layer = layer;

this.m_Area_FatherID = father;

}

}

#endregion

}

AreaControl.cs:

using System;

using System.Collections.Generic;

using Downmoon.Framework.Model;

namespace Downmoon.Framework.Controllers

{

public class AreaList : IArea

{

// Area singleton

private static AreaList instance;

public static AreaList Instance

{

get

{

if (AreaList.instance == null)

{

AreaList.instance = new AreaList();

}

return AreaList.instance;

}

}

public List GetAreaList()

{

List Areas = new List();

Areas.Add(new Area("110000", "北京市", 0, 1, "000000"));

Areas.Add(new Area("110100", "市辖区", 0, 2, "110000"));

Areas.Add(new Area("110101", "东城区", 0, 3, "110100"));

Areas.Add(new Area("110102", "西城区", 0, 3, "110100"));

Areas.Add(new Area("110103", "崇文区", 0, 3, "110100"));

Areas.Add(new Area("330000", "浙江省", 0, 1, "000000"));

Areas.Add(new Area("330100", "杭州市", 0, 2, "330000"));

Areas.Add(new Area("330200", "宁波市", 0, 2, "330000"));

Areas.Add(new Area("330102", "上城区", 0, 3, "330100"));

Areas.Add(new Area("330103", "下城区", 0, 3, "330100"));

Areas.Add(new Area("330104", "江干区", 0, 3, "330100"));

Areas.Add(new Area("330105", "拱墅区", 0, 3, "330100"));

Areas.Add(new Area("330106", "西湖区", 0, 3, "330100"));

Areas.Add(new Area("330203", "海曙区", 0, 3, "330200"));

Areas.Add(new Area("330204", "江东区", 0, 3, "330200"));

Areas.Add(new Area("330205", "江北区", 0, 3, "330200"));

Areas.Add(new Area("330206", "北仑区", 0, 3, "330200"));

Areas.Add(new Area("330211", "镇海区", 0, 3, "330200"));

return Areas;

}

public List GetAreaListFindByParentID(string filter)

{

return GetAreaList().FindAll(

delegate(Area ar)

{

return ar.Area_FatherID == filter;

}

);

}

}

}

Factory.cs

using System;

using System.Collections.Generic;

//using Downmoon.Framework.Model;

namespace Downmoon.Framework.Controllers

{

public class Factory

{

public static IArea GetAreaController()

{

return AreaList.Instance;

}

}

}

IArea.cs

using System;

using System.Collections.Generic;

using System.Text;

using Downmoon.Framework.Model;

namespace Downmoon.Framework.Controllers

{

public interface IArea

{

List GetAreaList();

List GetAreaListFindByParentID(string filterID);

}

}

一、基于aspnet自带的Ajax框架，主要好处是与asp.net完全集成，无需写过多的 js。缺点是在framework2下需作一些设置，在Framework 4下无需设置。

Framework 2：

需首先在web.config文件中作配置：

type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>

type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>

前台页面：

Framework 4：与代码完全一样，只是无需在web.config中作配置。

如图：

二、基于JQuery1.4.1的Ajax框架，主要好处是与后续版本的asp.net完全集成。

基于ashx作一个 Request，主要代码：

using System;

using System.Collections.Generic;

using System.Web;

using Downmoon.Framework.Controllers;

using Downmoon.Framework.Model;

using System.Text;

namespace dropdown_JQuery14_Net2

{

///

/// Summary description for AjaxRequest

///

public class AjaxRequest : IHttpHandler

{

public void ProcessRequest(HttpContext context)

{

string Area_FatherID = string.Empty;

if (context.Request["pid"] != null)

{ Area_FatherID = context.Request["pid"].ToString(); }

string parentId = string.Empty;

//mydbDataContext db = new mydbDataContext();

//根据传过来的Value值 进行查询

//List list = db.ChinaStates.Where(c => c.ParentAreaCode == strId).ToList();

List list = Factory.GetAreaController().GetAreaListFindByParentID(Area_FatherID);

context.Response.ContentType = "application/json";

context.Response.ContentEncoding = Encoding.UTF8;

context.Response.Write(ListToJson(list));

context.Response.End();

}

public string ListToJson(List list)

{

StringBuilder sb = new StringBuilder();

if (list != null)

{

sb.Append("[");

for (int i = 0; i < list.Count; i++)

{

sb.Append("{");

sb.Append("\"Area_ID\":\"" + list[i].Area_ID + "\",");

sb.Append("\"Area_Name\":\"" + list[i].Area_Name + "\"");

//sb.Append("\"Area_FatherID\":\"" + list[i].Area_FatherID + "\"");

if (i != list.Count - 1)

{

sb.Append("},");

}

}

}

sb.Append("}");

sb.Append("]");

return sb.ToString();

}

public bool IsReusable

{

get

{

return false;

}

}

}

}

前台：aspx

#dpCity

{

display: none;

position: relative;

}

#dpArea

{

display: none;

position: relative;

}

-->

{

display: none;

position: relative;

}

#dpArea

{

display: none;

position: relative;

}

三、基于ExtJS 3.2的Ajax框架。

后台ashx:

using System;

using System.Collections.Generic;

using System.Web;

using Downmoon.Framework.Controllers;

using Downmoon.Framework.Model;

using System.Text;

namespace dropdown_ExtJS32_Net2.Ajax

{

///

/// Summary description for GetAreaXml

///

public class GetAreaXml : IHttpHandler

{

//string baseCode = "000000";

public void ProcessRequest(HttpContext context)

{

string parentId = "000000";

if (context.Request["pid"] != null)

{

parentId = context.Request["pid"].ToString();

}

//parentId = (parentId.Length > 0) ? parentId : "000000";

string parentId2 = "000000";

if (context.Request["pid2"] != null)

{

parentId2 = context.Request["pid2"].ToString();

}

#region tony 2010.2.7 update

List list = new List();

//if (parentId.Length > 0)

//{

list = Factory.GetAreaController().GetAreaListFindByParentID(parentId);

//}

else if (parentId2.Length > 0)

{

list = Factory.GetAreaController().GetAreaListFindByParentID(parentId2);

}

#endregion

context.Response.AddHeader("Cache-Control", "no-cache, must-revalidate");

context.Response.ContentEncoding = System.Text.Encoding.UTF8;

context.Response.ContentType = "text/html";

StringBuilder sb = new StringBuilder();

for (int i = 0; i < list.Count; i++)

{

sb.Append("{\"Area_Name\":\"" + list[i].Area_Name + "\",");

sb.Append("\"Area_ID\":\"" + list[i].Area_ID + "\"},");

}

string json = sb.ToString().TrimEnd(',');

context.Response.Write("{\"Results\":[" + json + "]}");

}

public bool IsReusable

{

get

{

return false;

}

}

}

}

前台页面.aspx

demo a dropdownlist by extjs 3.2

请选择 省 市 县

效果如图：

邀月注：本文版权由邀月和CSDN共同所有，转载请注明出处。

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