List结果按照某个对象属性分类

//取各个批次中奖人列表
public Map<String,List<AniuAnnualMeetingRecord>> getAwardBatchList(){List<AniuAnnualMeetingRecord> list = aniuAnnualMeetingRecordMapper.getAwardBatchList();if(list == null || list.isEmpty()){return null;}TreeMap tm = new TreeMap();for(int i = 0; i < list.size(); i++){AniuAnnualMeetingRecord s = list.get(i);if(tm.containsKey(s.getBatchId())){ArrayList alist = (ArrayList)tm.get(s.getBatchId());alist.add(s);}else{ArrayList tem = new ArrayList();tem.add(s);tm.put(s.getBatchId(), tem);}}return tm;
}