省市联动初探AJAX操作数据

主要学习代码：

List.html

    <script type="text/javascript">

        function GetXhr() {

            return new XMLHttpRequest();

        }

        var getCities = function () {

            //alert(this.options[this.selectedIndex].value);

            //清空列表

            var cities = document.getElementById("sltCity");

            cities.options.length = 0;

            var id = this.options[this.selectedIndex].value;

            var xhr = GetXhr();

            xhr.open("post", "List.ashx", true);

            //post方式添加

            xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

            //post方式永远不会使用浏览器的缓存

            //设置不使用浏览器缓存

            //xhr.setRequestHeader("If-Modified-Since", "0");

            xhr.onreadystatechange = function () {

                if (xhr.readyState == 4 && xhr.status == 200) {

                    var json = eval(xhr.response);

                    for (var i = 0; i < json.length; i++) {

                        var node=document.createElement("option");

                        node.innerHTML=json[i].Name;

                        cities.appendChild(node);

                    }

                }

            };

            xhr.send("pId=" + id);

        };

        function getProvinces() {

            //创建异步请求对象

            var xhr = GetXhr();

            // alert(xhr.readyState);//0

            //设置参数

            xhr.open("get", "List.ashx", true);

            // alert(xhr.readyState);//1

            xhr.onreadystatechange = function () {

                // alert(xhr.readyState);//4

                if (xhr.readyState == 4) {

                    if (xhr.status == 200) {

                        // var s = [{ id: 1, name: 'value' }];

                        var cont = eval(xhr.responseText);

                        // alert(cont[0]);

                        //alert(cont.length);

                        var slt = document.getElementById("sltProvince");

                        for (var i = 0; i < cont.length; i++) {

                            slt.options[i] = new Option(cont[i].Name, cont[i].ID);

                        }

                    } else {

                        alert("服务器繁忙，请稍后在试。");

                    }

                }

            };

            //alert(xhr.readyState);//1

            //发送请求

            xhr.send();//post方式填写参数

            //alert(xhr.readyState);//1

        };

        window.onload = function () {

            getProvinces();

            document.getElementById("sltProvince").onchange = getCities;

        };

    </script>

</head>

<body>

    省：

    <select id="sltProvince">

    </select>

    &nbsp;市：<select id="sltCity">

    </select>

</body>

List.ashx:

<%@ WebHandler Language="C#" Class="List" %>

using System;

using System.Web;

using System.Collections.Generic;//List
//序列化命名空间

using System.Web.Script.Serialization;

public class List : IHttpHandler

{

    private Web.BLL.Transfer transfer = null;

    private List<Web.Model.PC> lpc = null;

    public void ProcessRequest(HttpContext context)

    {

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

        string id = context.Request.Form["pId"];

        if (!string.IsNullOrEmpty(id))

        {

            //第二种方式

            //市

            transfer = new Web.BLL.Transfer();

            JavaScriptSerializer serializer = new JavaScriptSerializer();

            lpc = transfer.GetProvincesOrCities(int.Parse(id));

            //这样返回的json自动以属性为键。

            //[{"Name":"白城市","Id":94},

            string json = serializer.Serialize(lpc);

            context.Response.Write(json);

        }

        else

        {

            //第一种方式

            //省

            transfer = new Web.BLL.Transfer();

            lpc = transfer.GetProvincesOrCities(0);

            System.Text.StringBuilder sb = new System.Text.StringBuilder(500);

            //拼接json字符串

            sb.Append("[");

            foreach (Web.Model.PC item in lpc)

            {

                sb.Append("{ID:" + item.Id + ",Name:'" + item.Name + "'},");

            }

            sb.Remove(sb.Length - 1, 1).Append("]");

            context.Response.Write(sb.ToString());

        }

    }

Web.BAL

    public class DataAction

    {

        private List<Web.Model.PC> lpc = null;

        private Web.Model.PC pc = null;

        public DataAction()

        {

            lpc = new List<Web.Model.PC>();

        }

        public List<Web.Model.PC> GetProvincesOrCities(int pId)

        {

            string sql = "select * from TblArea where AreaPId={0}";

            sql = string.Format(sql, pId);

            System.Data.DataTable dt = SqlHelper.ExecuteDataTable(sql);

            if (dt.Rows.Count > )

            {

                foreach (System.Data.DataRow item in dt.Rows)

                {

                    pc = new Web.Model.PC(int.Parse(item[].ToString()), item[].ToString());

                    lpc.Add(pc);

                }

            }

            return lpc;

        }

    }

项目文件：http://pan.baidu.com/s/1hq9Ro7E

巴特西

省市联动初探AJAX操作数据

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