ajax.net +jquery 无刷新三级联动的实例代码

    !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>
    title>/title>
    script src="Jquery1.7.js" type="text/javascript">/script>
    script type="text/javascript">
        $(function () {
            $.ajax({
                type: "post",
                contentType: "application/json",
                url: "WebService1.asmx/loadprovince",
                data: "{}",
                success: function (result) {
                    var ping;
                    for (var i = 0; i result.d.length; i++) {
                        ping += "option value=" + result.d[i].provinceID + ">";
                        ping += result.d[i].provincename;
                        ping += "/option>";

                    }
                    $('#Select1').append(ping);

   
                }

   
            })
            $('#Select1').change(function () {
                //第二次选时要记得清空市和县中的内容
                $('#Select2 option:gt(0)').remove();
                $('#Select3 option:gt(0)').remove();
                //在省的改变事件里绑定下一个下来列表（要失掉省的id）

                $.ajax({
                    type: "post",
                    contentType: "application/json",
                    url: "WebService1.asmx/loadcity",
                    data: "{fatherid:'" + $('#Select1 option:selected').val() + "'}",
                    success: function (result) {
                        var str2;
                        for (var i = 0; i result.d.length; i++) {
                            str2 += "option value=" + result.d[i].cityID + ">";
                            str2 += result.d[i].cityname;
                            str2 += "/option>";
                        }

                        $('#Select2').append(str2);
                    }
                })
            })
            $('#Select2').change(function () {
                $('#Select3 option:gt(0)').remove();

                $.ajax({
                    type: "post",
                    contentType: "application/json",
                    url: "WebService1.asmx/loadarea",
                    data: "{fatherid:'" + $('#Select2 option:selected').val() + "'}",
                    success: function (result) {
                        var str3;
                        for (var i = 0; i result.d.length; i++) {
                            str3 += "option value=" + result.d.areaID + ">";
                            str3 += result.d[i].areaname;
                            str3 += result.d[i].father;

                        }
                        $('#Select3').append(str3);
                    }
                })
            })
        })

    /script>
/head>
body>
   省：
    select id="Select1">
        option>--请选择--/option>
    /select>
    市：
    select id="Select2">
        option>--请选择--/option>
    /select>
    县：
    select id="Select3">
        option>--请选择--/option>
    /select>
/body>
/html>

 [WebMethod]//加载省
        public ListModel.province> loadprovince()//为什么要用list因为这里出从前的值不可能一个实例是多个model实例，一个实例就是一条记载这样做防止字段错误
        {
            BLL.province bp = new BLL.province();
            ListModel.province> list=bp.getlistModel();
            return list;
        }
        [WebMethod]//加载市
        public ListModel.city> loadcity(string fatherid)
        {
            BLL.city bc = new BLL.city();
            ListModel.city> list = bc.getlistmodel(fatherid);
            return list;
        }
        [WebMethod]//加载县
        public ListModel.area> loadarea(string fatherid)
        {
            BLL.area ba = new BLL.area();
            ListModel.area> list = ba.getlistmodel(fatherid);
            return list;

        }
    }
}

public System.Collections.Generic.ListModel.area> getlistmodel(string fatherid)
        {
            System.Collections.Generic.ListModel.area> list = new System.Collections.Generic.ListModel.area>();
            DataTable dt = GetList("father=" + fatherid + "").Tables[0];
            foreach (DataRow row in dt.Rows)
            {
                Model.area ma = new Model.area();
                ma.areaID = row["areaID"].ToString();
                ma.areaname = row["areaname"].ToString();
                ma.father = row["father"].ToString();
                list.Add(ma);
            }
            return list;
        }

 public System.Collections.Generic.ListModel.area> getlistmodel(string fatherid)
        {
            System.Collections.Generic.ListModel.area> list = new System.Collections.Generic.ListModel.area>();
            DataTable dt = GetList("father=" + fatherid + "").Tables[0];
            foreach (DataRow row in dt.Rows)
            {
                Model.area ma = new Model.area();
                ma.areaID = row["areaID"].ToString();
                ma.areaname = row["areaname"].ToString();
                ma.father = row["father"].ToString();
                list.Add(ma);
            }
            return list;
        }
    }

public System.Collections.Generic.ListModel.province> getlistModel()
        {
            //将要查的内容以实例的方式返回
            //这里要做的就是要建立list并将list用model实例填满，而model要用一个方法失掉数据并添加到model中
          //建list实例
            System.Collections.Generic.ListModel.province> list = new System.Collections.Generic.ListModel.province>();
            //已经有了的失掉数据的方法就不用自己写了通过调用Getlist的方法操纵数据库拿到数据
            DataTable dt = GetList("").Tables[0];
            //拿到数据后就需要将数据添加到model实例中了

            foreach (DataRow row in dt.Rows)
            {
                //每一行都是个实例所以要将model的放在循环里面
                Model.province mp = new Model.province();
                mp.provinceID = row["provinceID"].ToString();
                mp.provincename = row["provincename"].ToString();
                list.Add(mp);//没添加完一个实例都要放到list中
            }
            return list;

        }