private static final Logger logger = LogManager.getLogger(FessCrawlerThread.class);

    protected static final String CRAWLER_CLIENTS = "crawlerClients";

    protected ConcurrentHashMap<String, Pair<String, Pattern>> clientRuleCache = new ConcurrentHashMap<>();

    @Override
    protected boolean isContentUpdated(final CrawlerClient client, final UrlQueue<?> urlQueue) {
        if (ComponentUtil.getFessConfig().isIncrementalCrawling()) {

                    config.initializeClientFactory(() -> ComponentUtil.getComponent(CrawlerClientFactory.class));
            final CrawlerClient client = crawlerClientFactory.getClient(url);
            if (client == null) {
                throw new ThumbnailGenerationException("No CrawlerClient: " + configId + ", url: " + url);
            }
            String u = url;
            for (int i = 0; i < maxRedirectCount; i++) {

                }
            }
        }
    }

    protected CrawlerClient getClient(final String url) {
        return clientFactory.getClient(url);
    }

    protected boolean isContentUpdated(final CrawlerClient client, final UrlQueue<?> urlQueue) {
        if (urlQueue.getLastModified() != null) {

import org.codelibs.fess.crawler.helper.ContentLengthHelper;
import org.codelibs.fess.crawler.helper.MimeTypeHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * FileSystemClient is CrawlerClient implementation to crawl files on a file
 * system.
 *
 * @author shinsuke
 *
 */
public class FileSystemClient extends AbstractCrawlerClient {

                return;
            }

            final String url = dataMap.get(fessConfig.getIndexFieldUrl()).toString();
            final CrawlerClient client = crawlerClientFactory.getClient(url);
            if (client == null) {
                logger.warn("CrawlerClient is null. Data: {}", dataMap);
                return;
            }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.client.CrawlerClient#doGet(java.lang.String)
     */
    @Override
    public ResponseData doGet(final String uri) {
        return processRequest(uri, true);
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.client.CrawlerClient#doHead(java.lang.String)
     */
    @Override

        final CrawlerClientFactory crawlerClientFactory = crawlingConfig.initializeClientFactory(ComponentUtil::getCrawlerClientFactory);
        final CrawlerClient client = crawlerClientFactory.getClient(url);
        if (client == null) {
            throw new CrawlingAccessException("CrawlerClient is null for " + url);
        }

        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();

        assertEquals(5, testClient.count);
        assertEquals(url, response.getUrl());
        assertEquals(Constants.HEAD_METHOD, response.getMethod());
    }

    static class TestClient implements CrawlerClient {
        int count;

        int exceptionCount;

        long interval = 500;

        long previousTime;

        @Override

    }

    @Override
    public void close() {
        smbAuthenticationHolder = null;
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.client.CrawlerClient#doGet(java.lang.String)
     */
    @Override
    public ResponseData doGet(final String uri) {
        return processRequest(uri, true);
    }

        final CrawlerClient client = crawlerClientFactory.getClient(url);
        if (client == null) {
            throw new FessSystemException("No CrawlerClient: " + configId + ", url: " + url);
        }
        return writeContent(configId, url, client);
    }

    protected StreamResponse writeContent(final String configId, final String url, final CrawlerClient client) {