<select class=”chzn-select” id="CODE" name="CODE">
  ......
</select>

$(".chzn-select").chosen();

<!-- 省份 -->
<select class="chzn-select" id="ShengFen" name="ShengFen" onChange="setCity();" data-placeholder="请选择省份">
  <option value=""></option>
  <option value="">全部</option>
  <c:foreach items="${sfList}" var="sf">
   <option value="${sf.SF_ID}" <c:if test="${pd.sfId == sf.SF_ID}">selected</c:if${sf.SF_NAME} 
   </option>
  </c:foreach>
</select>
<!-- 城市 -->
<select class="chzn-select" id="City" name="City" data-placeholder="请选择城市">
  <option value=""></option>
  <option value="">全部</option>
  <c:foreach items="${cyList}" var="cy">
   <option value="${cy.CY_ID}" <c:if test="${pd.cyId == cy.CY_ID}">selected</c:if${cy.CY_NAME} 
   </option>
  </c:foreach>
</select>

//下拉框动态关联
function setCity(){
  // 获取选择的省份的ID
  var sfId = $("#ShengFen").val();
  $.ajax({
   type : "POST",
   url : "SFAndCity/setCity.do",
   data : {"sfId":sfId},
   dataType : "json",
   success : function(data){
     var cyList = data.cyList;
     // 移除以前的绑定数据
     $("#City option").remove();
     // 美化一下select（可以去除）
     var _option = "<option value=\"\"";
     _option += "></option>";
     _option += "<option value=\"\"";
     _option += ">全部</option>";
     // 绑定数据
     if(cfList && cyList.length != 0){
       $("select[name=City]").append(_option);
       for(var i=0;i<cyList.length;i++){
        var option = "<option value=\""+cyList.CY_ID+"\"";
        option += ">"+cyList.CY_NAME+"</option>";
        $("select[name=City]").append(option);
       }
     }else{
       $("select[name=City]").append(_option);
     }
     // 保证jQuery的选择插件动态绑定数据生效
     $("#City").trigger("liszt:updated");
     $("#City").chosen();
   }
  });
}

@RequestMapping(value="/setCity")
@ResponseBody
public Map<String,Object> setCity(){
  Map<String,Object> map = new HashMap<String,Object>();
  PageData pd = new PageData();
  try{
    pd = this.getPageData();
    String sfId = pd.getString("sfId"); //和ajax中传递的保持一致
    pd.put("CY_SFID",sfId);
    List<PageData> cyList = cyService.listCityBysfId(pd);
    map.put("cyList",cyList);  //和ajax中获取的保持一致
    return map;
  }catch(Exception e){
    
  }
  return map;
}