<select id="select" name="rawfoodBasic.category" onchange="doChange(this.value);">
//第一个下拉框里的值
</select>

<select id="subSelect" name="rawfoodBasic.absorb" onchange="javascript:alert(this.value);" > //要3及菜单还可以在次写相应的时间
<option value="0">--请选择二级菜单-- </option>
</select>

<script type="text/javascript">
$.ajaxSetup({
cache:false
}); //清除ajax中之前的值
function doChange(obj){
var url = '<c:url value="/nutrition/getSubDictDataToJsonByCategory.action"/>'+"?rawfood.category="+obj;//第一个下拉框选中后进入的action,action中给第二个下拉框所需的值赋值
$.getJSON(url,function(json){
var seleOjb=document.getElementById("subSelect");
for(var k=0;k<seleOjb.options.length;k++){
seleOjb.options.remove(k); //当再选中第一个下拉框中的值时,把第二个下拉框中原来的值清除
}
$.each(json.subCategoryDictList,function(index,subDictData){
var optionj=document.createElement("option"); //为第二个下拉框赋值
optionj.value = subDictData.id;
//alert(subDictData.id);
optionj.text=subDictData.name;
seleOjb.add(optionj);
});
});
}
</script>

<action name="getSubDictDataToJsonByCategory" class="rawfoodAction" method="getSubDictDataToJsonByCategory">
<result name="success" type="json">
<param name="includeProperties"> //定义返回的参数
^subCategoryDictList\[\d+\]\.id,
^subCategoryDictList\[\d+\]\.name
</param>
</result>
</action>