import com.google.common.cache.CacheBuilder;

public class PopularWordHelper {
    private static final Logger logger = LogManager.getLogger(PopularWordHelper.class);

    protected static final char CACHE_KEY_SPLITTER = '\n';

    protected Cache<String, List<String>> cache;

    protected FessConfig fessConfig;

    @PostConstruct
    public void init() {
        if (logger.isDebugEnabled()) {