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);
    }
    
}
?>