JQuery+WebService实现DropDownlist无刷新三级联动

本文的一些内容是参考互联网上的,所以有部分是相似的,请原作者谅解(时间久远,找不到出处了).

一,数据源为SQL Server

采用的是国内的省市县三级的数据库.具体的数据库请看脚本.
https://files.cnblogs.com/conan304/CitySQL.zip

二,前台代码端

    地址：&nbsp; &nbsp;<asp:DropDownList ID="ddlProvince" runat="server"></asp:DropDownList>
   &nbsp; &nbsp; <asp:DropDownList ID="ddlCity" runat="server"></asp:DropDownList> 

   &nbsp;&nbsp;<asp:DropDownList ID="ddlArea" runat="server"></asp:DropDownList>

   

三,Jquery代码

<script type="text/javascript" language="javascript" src="Script/jquery-1.4.1.min.js"></script>
<script type="text/javascript" language="javascript">
    $(function() {         

        var $dp1 = $("#ddlProvince");
        var $dp2 = $("#ddlCity");
        var $dp3 = $("#ddlArea");
        $dp1.focus();

        loadAreas("0", "0");

        $dp2[0].disabled = true;
        $dp3[0].disabled = true;

        $dp1.bind("change keyup", function() {
            if ($(this).val() != "") {
                var strPid = $dp1.attr("value"); //获取城市
                loadAreas(strPid, "1");
                $dp2[0].disabled = false;
            } else {
                $dp2[0].disabled = true;
                $("#ddlCity").html("");
                $("#ddlCity").append("<option value='' selected='selected'>请选择城市名称</option>");

                $("#ddlArea").html("");
                $("#ddlArea").append("<option value='' selected='selected'>请选择地区名称</option>");
            }
            $dp3[0].disabled = true;
        });
        $dp2.bind("change keyup", function() {
            var strCId = $dp2.attr("value"); //获取城市
            if ($(this).val() != "") {
                loadAreas(strCId, "2");
                $dp3[0].disabled = false;
            } else {
                $dp3[0].disabled = true;
                $("#ddlArea").html("");
                $("#ddlArea").append("<option value='' selected='selected'>请选择地区名称</option>");
            }
        });
    });

    function loadAreas(selectedItem, level) {
        $.ajax({
            type: "GET",
            contentType: "application/json; charset=utf-8",
            url: "Ajax/CityGet.asmx/CityInfoGet",
            data: encodeURI("parentID='" + selectedItem + "'"),
            dataType: "json",
            success: function(result) {
                switch (level) {
                    case "0":
                        $("#ddlProvince").html("");
                        $("#ddlProvince").append("<option value='' selected='selected'>请选择省份</option>");

                        $("#ddlCity").html("");
                        $("#ddlCity").append("<option value='' selected='selected'>请选择城市名称</option>");

                        $("#ddlArea").html("");
                        $("#ddlArea").append("<option value='' selected='selected'>请选择地区名称</option>");

                        for (var i = 0; i < result["d"].length; i++) {
                            $("#ddlProvince").append($("<option></option>").val(result["d"][i].CodeID).html(result["d"][i].CityName));
                        };
                        break;
                    case "1":
                        $("#ddlCity").html("");
                        $("#ddlCity").append("<option value='' selected='selected'>请选择城市名称</option>");

                        $("#ddlArea").html("");
                        $("#ddlArea").append("<option value='' selected='selected'>请选择地区名称</option>");

                        for (var i = 0; i < result["d"].length; i++) {
                            $("#ddlCity").append($("<option></option>").val(result["d"][i].CodeID).html(result["d"][i].CityName));
                        };
                        break;
                    case "2":
                        $("#ddlArea").html("");
                        $("#ddlArea").append("<option value='' selected='selected'>请选择地区名称</option>");
                        for (var i = 0; i < result["d"].length; i++) {
                            $("#ddlArea").append($("<option></option>").val(result["d"][i].CodeID).html(result["d"][i].CityName));
                        };
                        break;

                    default:
                        break;
                }

            },
            error: function(x, e) {
                alert(x.responseText);
            }
        });
    }

</script> 

四,c#代码 

1,WebService,位于AJAX文件夹下:

using System.Collections.Generic;
using System.Web.Script.Services;
using System.Web.Services;

/// <summary>
///CityGet 的摘要说明
/// </summary>
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
//若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。 
 [System.Web.Script.Services.ScriptService]
public class CityGet : System.Web.Services.WebService
{

    public CityGet()
    {

        //如果使用设计的组件，请取消注释以下行 
        //InitializeComponent(); 
    }


    /// <summary>
    /// 获取城市信息,用Json返回
    /// </summary>
    /// <param name="parentID"></param>
    /// <returns></returns>
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json, UseHttpGet = true)]
    public IList<Model.CityInfo> CityInfoGet(string parentID)
    {
        IList<Model.CityInfo> list = BLL.City.CityInfo.CityListFindByParentID(int.Parse(parentID));
        return list;
    }

} 

 多层架构调用,省略了中间的DALFactory,IDal等.这里仅仅写出访问数据库的代码:

using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Text;

namespace SQLServer.City
{
    public class CityInfo : IDAL.City.ICityInfo
    {
        /// <summary>
        /// 根据父级ID获取城市信息
        /// </summary>
        /// <param name="CodeID"></param>
        /// <returns></returns>
        public IList<Model.CityInfo> CityListFindByParentID(int CodeID)
        {
            IList<Model.CityInfo> listCity = new List<Model.CityInfo>();

            StringBuilder sql = new StringBuilder();
            sql.Append("    SELECT [codeid],[parentid],[cityName]");
            sql.Append("    FROM [tbl_province]");
            sql.Append("    WHERE parentid=@parentid");            
            sql.Append("    ORDER BY codeid");

            SqlParameter param = new SqlParameter("@parentid", SqlDbType.Int);
            param.Value = CodeID;


            using (SqlDataReader dr = SQLHelper.ExecuteReader(CommandType.Text, sql.ToString(), param))
            {
                while (dr.Read())
                {
                    Model.CityInfo city = new Model.CityInfo
                    {
                        CodeID = dr.GetInt32(0),
                        ParentID = dr.GetInt32(1),
                        CityName = dr.GetString(2).Trim()
                    };
                    listCity.Add(city);
                }
            }

            return listCity;
        }
    }

} 

Model:

namespace Model
{
    /// <summary>
    /// 城市信息
    /// </summary>
    public class CityInfo
    {
        /// <summary>
        /// 城市的ID
        /// </summary>
        public int CodeID { get; set; }

        /// <summary>
        /// 城市的父级ID
        /// </summary>
        public int ParentID { get; set; }

        /// <summary>
        /// 城市的名称
        /// </summary>
        public string CityName { get; set; }
    }

}