ajax实现无刷新两级联动DropDownList

本文来自小山blog:
http://singlepine.cnblogs.com/articles/257954.html
里面是三级联动,有数据库文件可下栽.
我只是将三级更改为两级,使用SQL SERVER数据库而已.

我的截图如下:
o_Ajax两级DropDownList联动.JPG
1.首先要在项目中增加对ajax.dll 的引用.

2.AjaxMethod.cs

using System;

using System.Data;

using System.Data.SqlClient;

namespace MyAjaxSample

{

/// <summary>

/// AjaxMethod 的摘要说明。

/// </summary>

public class AjaxMethod

{

#region GetPovinceList

public static DataSet GetPovinceList()

{

string sql="select * from povince";

return GetDataSet(sql);

}

#endregion

#region GetCityList

[Ajax.AjaxMethod]

public DataSet GetCityList(int povinceid)

{

string sql="select * from city where father='"+povinceid+"'";

return GetDataSet(sql);

}

#endregion

#region GetAreaList

[Ajax.AjaxMethod]

public DataSet GetAreaList(int cityid)

{

string sql="select * from area where father='"+cityid+"'";

return GetDataSet(sql);

}

#endregion

#region GetDataSet

public static DataSet GetDataSet(string sql)

{

string ConnectionString=System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];

SqlDataAdapter sda =new SqlDataAdapter(sql,ConnectionString);

DataSet ds=new DataSet();

sda.Fill(ds);

return ds;

}

#endregion

}

3.HTML代码:

<%@ Page language="c#" Codebehind="FourAjaxSample.aspx.cs" AutoEventWireup="false" Inherits="MyAjaxSample.FourAjaxSample" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >

<HTML>

<HEAD>

<title>FourAjaxSample</title>

function cityResult()

{

var city=document.getElementById("DropDownList1");

AjaxMethod.GetCityList(city.value,get_city_Result_CallBack);

}

function get_city_Result_CallBack(response)

{

if (response.value != null)

{

document.all("DropDownList2").length=0;　　　　

　　　　 var ds = response.value;

if(ds != null && typeof(ds) == "object" && ds.Tables != null)

{

for(var i=0; i<ds.Tables[0].Rows.length; i++)

　　　　 {

　　　　 var name=ds.Tables[0].Rows[i].city;

　　　　　　 var id=ds.Tables[0].Rows[i].cityID;

　　　　　　 document.all("DropDownList2").options.add(new Option(name,id));

　　　　 }

　　　　 document.all("TextBox1").value="";　　

}

return

}

function areaResult()

{

var area=document.getElementById("DropDownList2");

AjaxMethod.GetAreaList(area.value,get_area_Result_CallBack);

}

function get_area_Result_CallBack()

{

　　　　var province=document.getElementById("DropDownList1");

var pindex = province.selectedIndex;

var pValue = province.options[pindex].value;

var pText = province.options[pindex].text;

var city=document.getElementById("DropDownList2");

var cindex = city.selectedIndex;

var cValue = city.options[cindex].value;

var cText = city.options[cindex].text;

　　　　document.all("TextBox1").value=pText+cText;　　　　

}

</script>

</HEAD>

<h3>Ajax实现两级联动</h3>

<TABLE class="border" id="border" style="Z-INDEX: 101; LEFT: 16px; WIDTH: 289px; POSITION: absolute; TOP: 48px; HEIGHT: 79px"

borderColor="#95b0d9" cellSpacing="0" cellPadding="0" width="289" align="center" bgColor="#ffffff"

border="1">

<TR>

<asp:label id="Lab_province" runat="server">省(直辖市)</asp:label></TD>

<asp:dropdownlist id="DropDownList1" runat="server" onchange="cityResult();"></asp:dropdownlist></TD>

</TR>

<TR>

<asp:Label id="Lab_City" runat="server">城市</asp:Label></TD>

<asp:DropDownList id="DropDownList2" runat="server" onchange="areaResult();"></asp:DropDownList></TD>

</TR>

<TR>

<TD style="WIDTH: 130px" bgColor="#d8e7f6">你的最后选择是:

</TD>

<TD>

<asp:TextBox id="TextBox1" runat="server"></asp:TextBox></TD>

</TR>

</TABLE>

</form>

</body>

</HTML>

4 .cs文件:

using System;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Web;

using System.Web.SessionState;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.HtmlControls;

namespace MyAjaxSample

{

/// <summary>

/// FourAjaxSample 的摘要说明。

/// </summary>

public class FourAjaxSample : System.Web.UI.Page

{

protected System.Web.UI.WebControls.DropDownList DropDownList1;

protected System.Web.UI.WebControls.Label Lab_province;

protected System.Web.UI.WebControls.Label Lab_City;

protected System.Web.UI.WebControls.TextBox TextBox1;

protected System.Web.UI.WebControls.DropDownList DropDownList2;

private void Page_Load(object sender, System.EventArgs e)

{

Ajax.Utility.RegisterTypeForAjax(typeof(MyAjaxSample.AjaxMethod));

if(!Page.IsPostBack)

{

this.DropDownList1.DataSource=AjaxMethod.GetPovinceList();

this.DropDownList1.DataTextField="province";

this.DropDownList1.DataValueField="provinceID";

this.DropDownList1.DataBind();

this.DropDownList1.Attributes.Add("onclick","cityResult();");

this.DropDownList2.Attributes.Add("onclick","areaResult();");

}

#region Web 窗体设计器生成的代码

override protected void OnInit(EventArgs e)

{

// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。

InitializeComponent();

base.OnInit(e);

}

/// <summary>

/// 设计器支持所需的方法 - 不要使用代码编辑器修改

/// 此方法的内容。

/// </summary>

private void InitializeComponent()

{

this.Load += new System.EventHandler(this.Page_Load);

}

#endregion

}

5.web.config

web.config设置数据库连接串