Map的value取得key
转载http://hi.baidu.com/sonos/item/2510a3166cb377c838cb30a4

protected List getKeyByValue(Map map, Object value) {List keys = new ArrayList();Iterator it = map.entrySet().iterator();while (it.hasNext()) {Map.Entry entry = (Entry) it.next();Object obj = entry.getValue();if (obj != null && obj.equals(value)) {keys.add(entry.getKey());}}return keys;}