code: private List<CacheObject> sort() {
  		List<CacheObject> cacheObjectList = new ArrayList<CacheObject>(cache.values());
  
  		if (config.getSortLength() != 0) {
  			int end = config.getSortLength();
  			if (cacheObjectList.size() < config.getSortLength()) {
  				end = cacheObjectList.size();
  			}
  			cacheObjectList = cacheObjectList.subList(0, end);
  		}
  		Collections.sort(cacheObjectList, config.getEvictionPolicy());
  
  		return cacheObjectList;
  	}
docs: /*
  更新缓存对象的顺序