DropDownList无刷新级联下拉（固定级联），Jquery获取JOSN数据

1.HTML页面

<td align="left">
                                <asp:DropDownList ID="ddlOne" runat="server">
                                </asp:DropDownList>
                                <asp:DropDownList ID="ddlTwo" runat="server">
                                </asp:DropDownList>
</td>

ddlOne的绑定这里就不说了，后台直接绑定即可，关键是选择ddlOne的时候页面无刷新的级联ddlTwo。

首先添加ddlOne的选择事件

 this.ddlOne.Attributes.Add("OnChange", "BindDropDownList()");

2.BindeDropDownList()方法读取ashx，以获取父类ID等于ddlOne选中值的集合，这里我们用JOSN方式获取

function BindDropDownList() {
    var one = $("#ddlOne").val();
    $("#ddlTwo").html("");
    $.getJSON("../Customer/Area.ashx?parentid=" + one, null, function(json) {
        $.each(json, function(i) { $("#ddlTwo").append($("<option></option>").val(json[i].areacode).html(json[i].areaname)) });
    });
    $("<option></option>").val("-1").html("---请选择城市---").appendTo("#ddlTwo");
}

2.area.ashx

public void ProcessRequest(HttpContext context)
        {
            StringBuilder sb = new StringBuilder();
            string strparent = context.Request.QueryString["parentid"].ToString();
            string strwhere = " areacode like '" + strparent.Substring(0, 2) + "%' and areacode not like '%0000'";//取得子类
            DataTable dt = new BLL.SF_Host_AreaInfo().GetList(strwhere).Tables[0];
            if (dt == null || dt.Rows.Count == 0)
            {
                return;
            }
            else
            {
                sb.Append("[");
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    //返回JOSN数据
                    sb.Append("{\"areacode\":\"" + dt.Rows[i]["areacode"].ToString() + "\",\"areaname\":\"" + dt.Rows[i]["areaname"].ToString() + "\"},");
                }
                sb.Remove(sb.Length - 1, 1);
                sb.Append("]");
            }
            context.Response.ContentType = "application/json";
            context.Response.ContentEncoding = Encoding.UTF8;
            context.Response.Write(sb.ToString());
        }