code: public void put(String key, Object value, long time, TimeUnit unit) {
          Object oldValue = cacheObjMap.put(key, value);
          if (oldValue != null){
          	MicroDelayItem temp=new MicroDelayItem(key,0);
              q.remove(temp);
          }
  
          long nanoTime = TimeUnit.NANOSECONDS.convert(time, unit);
          q.put(new MicroDelayItem(key, nanoTime));
      }
docs: 添加缓存对象