JS+AJAX realizes the linkage of province, city and district drop-down lists

<div class="info">
<div class="title">Company Address:</div>
<div class="value">
<fieldset disabled>
<select id="provinceSelect" class="form-control" data-val="${factoryCenterInfo.province}" onchange="provinceChange()">
<c:forEach items="${factoryPlace.provinceList}" var="province" varStatus="status">
<option value="${province.key}" <span style="color:#3333ff;"><c:if test="${factoryCenterInfo.province == province.key}">selected</c:if></span><span style="color:#3366ff;">></span>${province.value}</option>
</c:forEach>
</select>
</fieldset>
<fieldset disabled>
<select id="citySelect" class="form-control" data-val="${factoryCenterInfo.city}" onchange="cityChange()">
<c:forEach items="${factoryPlace.cityList}" var="city" varStatus="status">
<option value="${city.key}" <span style="color:#3333ff;"><c:if test="${factoryCenterInfo.city == city.key}">selected</c:if></span>>${city.value}</option>
</c:forEach>
</select>
</fieldset>
<fieldset disabled>
<select id="areaSelect" class="form-control" data-val="${factoryCenterInfo.area}">
<c:forEach items="${factoryPlace.areaList}" var="area" varStatus="status">
<option value="${area.key}" <span style="color:#3333ff;"><c:if test="${factoryCenterInfo.area == area.key}">selected</c:if></span>>${area.value}</option>
</c:forEach>
</select>
</fieldset>
</div>
</div>

function provinceChange(){
 
 var provinceId = $("#provinceSelect").val();
 $("#citySelect").empty();
 $("#areaSelect").empty();
 
 if(provinceId != null && provinceId != ""){
  
  $.ajax({
   type: "POST",
   url:"<span style="color:#3333ff;">factory/getChangeList</span>",
   dataType:'json',
   data: {
    "parentId":provinceId,
    "placeKbn":"C"
   },
   cache:false,
   success: function(data){
    if("success" == data.result){
     if(data.cityList != null && data.cityList.length > 0){
      for(var i = 0;i < data.cityList.length;i++){
       var city = data.cityList[i];
       var key = (city.key == null? "":city.key);
       var value = (city.value == null? "":city.value);
       $("#citySelect").append("<option value = \"" + key + "\">"+ value + "</option>");
      }
     }else{
      $("#citySelect").append("<option> </option>");
     }
     $("#areaSelect").append("<option> </option>");
    }
    if("error" == data.result){
     $("#citySelect").append("<option> </option>");
     $("#areaSelect").append("<option> </option>");
    }
   },
   error:function(XMLHttpRequest, textStatus, errorThrown){
       $("#errorContent").html("System abnormality, please contact the administrator");
      }
   
  });
 }else{
  $("#citySelect").append("<option> </option>");
  $("#areaSelect").append("<option> </option>");
 }
}
 
function cityChange(){
 
 var cityId = $("#citySelect").val();
 
 $("#areaSelect").empty();
 
 if(cityId != null && cityId != ""){
  
  $.ajax({
   type: "POST",
   url:"<span style="color:#3333ff;">factory/getChangeList</span>",
   dataType:'json',
   data: {
    "parentId":cityId,
    "placeKbn":"Q"
   },
   cache:false,
   success: function(data){
    if("success" == data.result){
     if(data.areaList != null && data.areaList.length > 0){
      for(var i = 0;i < data.areaList.length;i++){
       var area = data.areaList[i];
       var key = (area.key == null? "":area.key);
       var value = (area.value == null? "":area.value);
       $("#areaSelect").append("<option value = \"" + key + "\">"+ value + "</option>");
      }
     }else{
      $("#areaSelect").append("<option> </option>");
     }
    }
    if("error" == data.result){
     $("#areaSelect").append("<option> </option>");
    }
   },
   error:function(XMLHttpRequest, textStatus, errorThrown){
       $("#errorContent").html("System abnormality, please contact the administrator");
      }
   
  });
 }else{
  $("#citySelect").append("<option> </option>");
  $("#areaSelect").append("<option> </option>");
 }
}

@RequestMapping("<span style="color:#3333ff;">getChangeList</span>")
 @ResponseBody
 public Object getChangeList(String parentId,String placeKbn){
  logBefore(logger, "factory/getChangeList");
  Map<String,Object> returnMap = new HashMap<String,Object>();
  
  if (FactoryConsts.CHAR_KBN_CITY.equals(placeKbn)) {
   if(getPlacelist( parentId, placeKbn) != null && getPlacelist( parentId, placeKbn).size() > FactoryConsts.INT_0){
    returnMap.put("result", "success");
    returnMap.put("cityList", getPlacelist(parentId, placeKbn));
   }else{
    returnMap.put("error", "city list is empty");
    returnMap.put("cityList", "");
   }
   
  }else if(FactoryConsts.CHAR_KBN_AREA.equals(placeKbn)){
   if(getPlacelist( parentId, placeKbn) != null && getPlacelist( parentId, placeKbn).size() > FactoryConsts.INT_0){
    returnMap.put("result", "success");
    returnMap.put("areaList", getPlacelist(parentId, placeKbn));
   }else{
    returnMap.put("error", "area list is empty");
    returnMap.put("areaList", "");
   }
  }
  return returnMap;
 }
 /**
  *Province drop-down list* 
  * @return
  */
 private List<PlaceOption> getPlacelist(String parentId,String kbn){
  //Drop-down list List<PlaceOption> placeList = new ArrayList<PlaceOption>();
  placeList.add(new PlaceOption());
  QueryPlaceInfoParam queryParam = new QueryPlaceInfoParam();
  queryParam.setPlaceKbn(kbn);
  if(!StringUtils.isEmpty(parentId)){
   queryParam.setPlaceId(Integer.valueOf(parentId));
  }
  FactoryPlaceNameResult placeResult = placeInfoService.queryPlaceInfo(queryParam);
  
  if(placeResult != null && "0".equals(placeResult.getResult()) 
    && placeResult.getPlaceInfo() != null 
    && placeResult.getPlaceInfo().size() > FactoryConsts.INT_0){
   List<PlaceInfoFa> placeInfo = new ArrayList<PlaceInfoFa>();
   placeInfo = placeResult.getPlaceInfo();
   for(FactoryPlaceInfo info : placeInfo){
    PlaceOption option = new PlaceOption();
    option.setKey(String.valueOf(info.getPlaceId()));
    option.setValue(info.getPlaceName());
    placeList.add(option);
   }
  }
  
  return placeList;
 }

/**
  * Basic information initialization method * 
  * @param request
  * @return
  */
 @RequestMapping("toFactoryBaseInfo")
 public ModelAndView toFactoryBaseInfo(HttpServletRequest request){
  logBefore(logger, "factory/toFactoryBaseInfo");
  ModelAndView mv = new ModelAndView();
  //Enterprise type Map<String,String> factoryTypeMap = new TreeMap<String,String>();
  factoryTypeMap.putAll(FactoryConsts.FACTORY_TYPE_MAP);
  mv.addObject("factoryTypeMap", factoryTypeMap);
  
  FactoryFactoryInfo factoryInfo = (FactoryFactoryInfo) request.getSession().getAttribute(Const.SESSION_FACTORY);
 
  //Get enterprise information FactoryFactoryInfoParam infoParam = new FactoryFactoryInfoParam();
             FactoryFactoryInfoResult infoResult = new FactoryFactoryInfoResult();
  infoParam.setFactoryId(String.valueOf(factoryInfo.getFactoryId()));
  infoParam.setDifferent(FactoryConsts.STRING_WEB_ONE); //web
  infoResult = factoryService.factoryInfo(infoParam);
 
  FactoryPlace factoryPlace = new FactoryPlace();
  
  <span style="color:#3333ff;">// Province drop-down list factoryPlace.setProvinceList(getPlacelist("0",FactoryConsts.CHAR_KBN_PROVINCE));
  // City drop-down list factoryPlace.setCityList(getPlacelist(infoResult.getFactoryInfoEx().getProvince(),FactoryConsts.CHAR_KBN_CITY));
  // Area drop-down list factoryPlace.setAreaList(getPlacelist(infoResult.getFactoryInfoEx().getCity(),FactoryConsts.CHAR_KBN_AREA));</span>
  
  <span style="color:#cc66cc;">mv.addObject("factoryPlace", factoryPlace);//List of addresses</span>
  <span style="color:#6633ff;">mv.addObject("factoryCenterInfo", infoResult.getFactoryInfoEx());//Basic information of the enterprise table</span>
  mv.setViewName("factory/factoryInformationCenter/saveFactoryBaseInfo");
  return mv;
 }