public class JsonUtil {

    /**
     * 将json转化成map
     * @param jsonStr
     * @return
     */
    public static Map<String, Object>   convertJsonStrToMap(String jsonStr){

        Map<String, Object> map = JSON.parseObject(
                jsonStr,new TypeReference<Map<String, Object>>(){} );

        return map;
    }
}

        String jsonData = "{id:100,list:[{a:1},{a:2}]";
        Map<String, Object> map = JsonUtil.convertJsonStrToMap(jsonData);
        System.out.println(map);
        Integer id = MapUtils.getInteger(map, "id");
        Object list = MapUtils.getObject(map, "list");
        List<JSONObject> ll = (List)list;
        for (JSONObject s : ll) {
            String eleVal = s.get("a").toString();
            System.out.println(s+"---a的值是："+eleVal);
        }