Easyui 加载树（easyui-tree）[dotnet]

前台  html：
<ul class="easyui-tree" id="ul_Tree" data-options="fit:true,animate:true"></ul>

javascript 加载
$("#ul_Tree").tree({
        url: '/webservice/CreditExtension/CreditExtension.asmx/QueryImages?Hid_FileCode=' + $("#Hid_FileCode").val() + "&imgstyle=0&r=" + new Date().getMilliseconds(),
        method: 'get',
        onSelect: function (note) {
            if (note.attributes != undefined && note.attributes != "") {
                var style = note.attributes.substr(note.attributes.lastIndexOf("."), note.attributes.length - note.attributes.lastIndexOf("."));
                if (style == ".bmp" || style == ".gif" || style == ".jpg" || style == ".png" || style == ".jpeg") {
                    setTheFirst(note.attributes);
                    $("#img_show").attr("src", note.attributes);
                    $("#div_title").html(note.text);
                } else { window.open(note.attributes, "preview", ""); }
            }
            else { $("#ul_Tree").tree("toggle", note.target); }
        }
    });

后台返回json：
public string GetToTreeJson(DataSet ds)
{
	 StringBuilder result = new StringBuilder();
	 result.Append("[");
            foreach (DataRow dr in ds.Tables[0].Rows)
            {
                result.Append("{"id":0,"text":"" + dr["text"].ToString() + "","iconCls":"icon-hkb"");
                DataRow[] drs = ds.Tables[1].Select(" parent_id='" + dr["id"].ToString() + "'");
                if (drs.Length > 0)
                {
                    result.Append(","state":"closed","children":[");
                    for (int i = 0; i < drs.Length; i++)
                    {
                        if (i > 0) result.Append(",");
                        result.Append("{"id":" + drs[i]["id"].ToString() + ","text":"" + drs[i]["text"].ToString() + "","attributes":"" + imgpath + formatString(drs[i]["attributes"].ToString()) + "","iconCls":"icon-" + getStyle(drs[i]["attributes"]) + ""}");
                    }
                    result.Append("]");
                }
                else
                {
                    result.Append(","state":"open"");
                }
                result.Append("},");
            }
            result.Remove(result.Length - 1, 1);
            result.Append("]");
	return result.toString();
}