java利用反射机制获取list中的某个字段并以list形式返回

public static<T> List<Object> listToList(Collection<T> list,String fieldName) throws Exception {
   List<Object> ret = new ArrayList();
   List<String>getStrs=null;
   List<Method> getMethods=new ArrayList<Method>();
   for(T t:list){
      if(getStrs==null){
         getStrs = new ArrayList<String>();
         for(String s:fieldName.split("\.")){
            getStrs.add("get"+s.substring(0,1).toUpperCase()+s.substring(1));
         }
      }
      Object value = t;
      for(int i=0;i<getStrs.size();i++){

         if(getMethods==null || getMethods.size()<=i ||getMethods.get(i)==null){
            getMethods.add(value.getClass().getDeclaredMethod(getStrs.get(i)));
         }
         value=getMethods.get(i).invoke(value);
      }
      ret.add(value);
   }
   return ret;
}