@Override
    public String get(Integer key) {
        if (key == null || key < 0) {
            return null;
        }
        int route = key / BATCH_COUNT;
        ArrayList<String> dataList = activeCache.get(route);
        if (dataList == null) {
            dataList = fileCache.get(route);
            activeCache.put(route, dataList);
            if (log.isDebugEnabled()) {
                if (cacheMiss++ % DEBUG_CACHE_MISS_SIZE == 0) {
                    log.debug("Cache misses count:{}", cacheMiss);
                }
            }
        }
        return dataList.get(key % BATCH_COUNT);
    }
Count the number of cache misses
fastexcel-core/src/main/java/cn/idev/excel/cache/Ehcache.java