easyui 的combobox二级联动

jsp页面

     公路行政级别: 

         
     路线编码: 
           					 		             

js代码

$(function() {
    var _adminLevel = $('#adminLevel').combobox({
    	data    :jsongl_xzjb,
    	method  :'get',
        editable: false,
        valueField:'CODE',
        textField:'CODETEXT',
        onSelect: function (record) {
            _zhbid.combobox({
                disabled: false,
                url: "BaseRoadSeg.ered?reqCode=selectRoadName&adminLevel=" + record.CODE,
                valueField: 'roadNo',
                textField: 'roadName'
            }).combobox('clear');
        }
    });
    var _zhbid = $('#roadNo').combobox({
        disabled: true,
        valueField: 'roadNo',
        textField: 'roadName'
    });

  }); 

后台Java代码逻辑

	public ActionForward selectRoadName(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		String adminLevel="";
		if(G4Utils.isNotEmpty(request.getParameter("adminLevel"))){
			//解决中文乱码
		   adminLevel = new String(request.getParameter("adminLevel").getBytes("GBK"), "utf-8");
		}        
        List listLaws = g4Reader.queryForList("BaseRoad.getBaseRoadDtoByadminLevel", adminLevel);
        String jsonString = JsonHelper.encodeObject2Json(listLaws); 
        write(jsonString, response);
        return mapping.findForward(null);        
	}

sql语句

  
		select roadNo,roadName from BASE_ROAD WHERE adminLevel=#adminLevel# and cancelFlag=0
  

返回的数据格式

[{
"roadNo":"1111",
"roadName":"111"},
{"roadNo":"453454",
"roadName":"5345"},
{"roadNo":"55345",
"roadName":"4534"
}]