Detailed explanation of how Asp.Net+jQuery realizes the secondary linkage function of provinces and cities-C#.Net Tutorial-php.cn

Detailed explanation of how Asp.Net+jQuery realizes the secondary linkage function of provinces and cities

黄舟

Release： 2017-06-04 09:49:19

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This article mainly introduces the method of jQuery+Asp.Net to realize the secondary linkage function of provinces and cities, involving asp.net database reading and stringConversion related operation skills, friends in need can refer to the following

The example of this article describes the method of jQuery+Asp.Net to realize the secondary linkage function of provinces and cities. Share it with everyone for your reference, the details are as follows:

Page 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=&#39;" + value.value + "&#39;>" + 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=&#39;" + value.value + "&#39;>" + 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=&#39;" + value.value + "&#39;>" + value.text + "</option>");
});
});
});
});
</script>
</head>
<body>
<form id="form1" runat="server">
<p>
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>
</p>
</form>
</body>
</html>

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asp.net part:

(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)+"]");
  }
}

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(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=&#39;" + fid + "&#39;";
      //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&#39;逗号&#39;
    }
  }
  public bool IsReusable {
    get {
      return false;
    }
  }
}

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