JSP页面中下拉框级联的实现

核心提示：String eduLevelId=request.getParameter("eduLevelId"); if(gradeName==null||gradeName.equals("0")){ gradeName="null";}if(eduLev

String eduLevelId=request.getParameter("eduLevelId");
if(gradeName==null||gradeName.equals("0")){
gradeName="null";
}
if(eduLevelId==null||eduLevelId.equals("0")){
eduLevelId="null";
}
ArrayList<UtilObject> eduLevelList=uess.getEduLevelIdByGradeNameInSpecialDetail(gradeName);
ArrayList<UtilObject> specialIdList=uess.getSpecialIdByGradeNameAndEduLevelIdInSpecialDetail(gradeName, eduLevelId);
mav.addObject("educationLevel", eduLevelList);
mav.addObject("specialList", specialIdList);
mav.setViewName("scoreManage/uniExamScore/eduLevelAndSpecialAjax");
return mav;
}
@RequestMapping(value = "/specialByGradeNameAndEduLevelIdInSpecialDetail", method = RequestMethod.POST)
public ModelAndView getSpecialByGradeNameAndEduLevelIdInSpecialDetail(HttpServletRequest request,
HttpServletResponse response) throws JsonParseException, JsonMappingException, JSONException, IOException{
String gradeName=request.getParameter("grade");
String eduLevelId=request.getParameter("eduLevelId");
System.out.println("grade:"+gradeName+" eduLevelId:"+eduLevelId);
if(gradeName==null||gradeName.equals("0")){
gradeName="null";
}
if(eduLevelId==null||eduLevelId.equals("0")){
eduLevelId="null";
}
ArrayList<UtilObject> specialList=uess.getSpecialIdByGradeNameAndEduLevelIdInSpecialDetail(gradeName, eduLevelId);
mav.addObject("specialList", specialList);
mav.setViewName("scoreManage/uniExamScore/specialAjax");
return mav;
}

Controller代码：
后台代码没有给出来，但应该看得懂，就是获取后台数据传到JSP页面，就是获取后台数据传到eduLevelAndSpecialAjax.jsp和specialAjax.jsp页面。这两个页面用于填充原页面，通过ID来填充相应区域，两个页面代码如下。
eduLevelAndSpecialAjax.jsp页面：
<td id="refreshEduLevelAndSpecialAjax"> //ID用于填充原页面
<table>
<tr>
<td width="400px" align="left">层　　　 次：<select
id="eduLevelId" name="eduLevelId" onchange="refreshSpecialAjax();">
<option value="0">--请选择--</option>
<c:forEach items="${educationLevel}" var="educationLevel">
<option value="${educationLevel.id}">${educationLevel.name}</option>
</c:forEach>
</select></td>
<td width="400px" align="left" id="refreshSpecialAjax">专　　　　业：<SELECT //ID用于填充原页面
NAME="specialId" id="specialId">
<option value="0">--请选择--</option>