页面html:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ddlAjax.aspx.cs" Inherits="ThreeAjaxDrop_ddlAjax" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>DropDownList三级联动</title>
<style type="text/css">
*{margin:0; padding:0;}
body{font-size:12px; font-family:Arial @宋体;}
</style>
<script type="text/javascript" src="../js/jquery-1.4.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
//加载完成后绑定省份数据
$.getJSON("Default.aspx", function(data) { //data的数据格式[{"text":"北京","value":"0001"},{"text":"江西","value":"0031"}]
//alert(data[0].text+"|"+data[0].value);
$.each(data, function(index, value) {
//alert(value.text + "|" + value.value);
$("#selProvince").append("<option value='" + value.value + "'>" + value.text + "</option>");
});
});
//省份的值改变，则要绑定出城市下拉框
$("#selProvince").change(function(){
document.getElementById("selArea").options.length=1; //先清掉县下拉框的的数据
document.getElementById("selCity").options.length=1; //先清掉城市下拉框的的数据
$.getJSON("HandlerDropDownAjax.ashx",{"type":"city","fid":$(this).val()},function(data){
$.each(data, function(index, value) {
$("#selCity").append("<option value='" + value.value + "'>" + value.text + "</option>");
});
});
});
//城市下拉框的值改变
$("#selCity").change(function(){
document.getElementById("selArea").options.length=1; //先清掉县下拉框的的数据
$.getJSON("HandlerDropDownAjax.ashx",{"type":"area","fid":$(this).val()},function(data){
$.each(data, function(index, value) {
$("#selArea").append("<option value='" + value.value + "'>" + value.text + "</option>");
});
});
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
三级联动：<select id="selProvince">
<option value="选择省份">==选择省份==</option>
</select> <select id="selCity"><option>==选择城市==</option></select>& amp;nbsp; <select id="selArea"><option>==选择县==</option></select>
</div>
</form>
</body>
</html>
asp.net:(1)Default.aspx.cs
public partial class ThreeAjaxDrop_Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string sql = "select * from province"; string strTemp = ""text":"{0}","value":"{1}""; //构造格式字符串 {"text":"北京","value":"00001"} StringBuilder sb = new StringBuilder(); OleDbDataReader reader = OleDBHelper.ExecuteReader(sql); while (reader.Read()) { string str1 = string.Format(strTemp, reader["province"].ToString(), reader["provinceID"].ToString()); sb.Append("{"+str1+"},"); } reader.Close(); string json = sb.ToString(); Response.Write("["+json.Substring(0,json.Length-1)+"]"); } } (2)HandlerDropDownAjax.ashx public class HandlerDropDownAjax : IHttpHandler { public void ProcessRequest (HttpContext context) { if (context.Request.QueryString["type"] != null && context.Request.QueryString["fid"] != null) { string type = context.Request.QueryString["type"].ToString(); //主要用于识别是查询city还是area表 string fid = context.Request.QueryString["fid"].ToString(); //城市或区域的父ID string sql = "select * from " + type + " where father='" + fid + "'"; //构造数据的类型[{"text":"南昌","value":"0001"},{"text":"上饶","value":"0002"}] //string strTemp = "{"text":"{0}","value":"{1}"}";//这里犯了个错误：直接这样构造会出错，因为大括号里又有格式大括号，解析会出错 string strTemp = ""text":"{0}","value":"{1}""; //构造格式字符串 {"text":"北京","value":"00001"} StringBuilder sb = new StringBuilder(); OleDbDataReader reader = OleDBHelper.ExecuteReader(sql); while (reader.Read()) { string str1 = string.Format(strTemp, reader[2].ToString(), reader[1].ToString()); sb.Append("{" + str1 + "},"); //两边的大括号格式化后加上 } reader.Close(); string json = sb.ToString(); context.Response.Write("[" + json.Substring(0, json.Length - 1) + "]"); //Substring的作用是去掉最后一个'逗号' } } public bool IsReusable { get { return false; } } }