Thinkphp dwz 三级联动下拉菜单

Tpl\ComBox\index.html：

<h2 class="contentTitle">下拉菜单</h2><div class="pageContent" layoutH="56"><select class="combox" name="province" ref="w_combox_city" refUrl="__URL__/returnCity/cityId/{value}"><option value="all">所有省市</option><option value="bj">北京</option><option value="sh">上海</option></select><select class="combox" name="city" id="w_combox_city" ref="w_combox_area" refUrl="__URL__/returnArea/areaId/{value}"><option value="all">所有城市</option></select><select class="combox" name="area" id="w_combox_area"><option value="all">所有区县</option></select></div>

Action\ComBoxAction.class.php：

<?php// 三级联动下拉菜单class ComBoxAction extends CommonAction {             public function returnCity(){        $cityId = $_REQUEST['cityId'];        if($cityId=='sh'){            $arrCity = array(array('all','所有城市'),array('sh','上海市'));        }else if($cityId=='bj'){            $arrCity = array(array('all','所有城市'),array('bj','北京市'));        }else{            $arrCity = array(array('all','所有城市'));        }         echo json_encode($arrCity);    }        public function returnArea(){        $areaId = $_REQUEST['areaId'];        if($areaId=='sh'){            $arrArea = array(array('1','上海城市1'),array('2','上海城市2'));        }else if($areaId=='bj'){            $arrArea = array(array('3','北京城市3'),array('bj','北京城市4'));        }else{            $arrArea = array(array('all','所有城市'));        }                 echo json_encode($arrArea);    }    }?>