* @throws CrawlingAccessException If the FTP request fails
     */
    protected ResponseData processRequest(final String uri, final boolean includeContent) {
        if (ftpAuthenticationHolder == null) {
            init();
        }

        // start
        AccessTimeoutTarget accessTimeoutTarget = null;
        TimeoutTask accessTimeoutTask = null;
        if (accessTimeout != null) {

            crawlerContext.activeThreadCount--;
        }
    }

    /**
     * Checks if the crawling process should continue.
     * @param tcCount The thread check count.
     * @return true if the crawling should continue, false otherwise.
     */
    protected boolean isContinue(final int tcCount) {
        if (!crawlerContainer.available()) {
            // system shutdown
            return false;
        }

     */
    public void addExtractor(final String key, final Extractor extractor) {
        if (StringUtil.isBlank(key)) {
            throw new CrawlerSystemException("The key is null.");
        }
        if (extractor == null) {
            throw new CrawlerSystemException("The extractor is null.");
        }
        if (extractorMap.containsKey(key)) {
            final Extractor[] existingExtractors = extractorMap.get(key);

     * @return the embedded file, or null if not found
     */
    protected PDEmbeddedFile getEmbeddedFile(final PDComplexFileSpecification fileSpec) {
        // search for the first available alternative of the embedded file
        PDEmbeddedFile embeddedFile = null;
        if (fileSpec != null) {
            embeddedFile = fileSpec.getEmbeddedFileUnicode();
            if (embeddedFile == null) {

     * If the property is not already set, it will be initialized with this package.
     * If the property is set but does not contain this package, the package will be appended.
     */
    default void initialize() {
        final StringBuilder buf = new StringBuilder(100);
        final String value = System.getProperty("java.protocol.handler.pkgs");
        if (StringUtil.isEmpty(value)) {

        if (url != null) {
            builder.field(URL, url);
        }
        if (parentUrl != null) {
            builder.field(PARENT_URL, parentUrl);
        }
        if (status != null) {
            builder.field(STATUS, status);
        }
        if (httpStatusCode != null) {
            builder.field(HTTP_STATUS_CODE, httpStatusCode);
        }
        if (method != null) {

        String modeSetting = settings.get("mode", null);
        if (modeSetting != null) {
            if ("search".equalsIgnoreCase(modeSetting)) {
                mode = JapaneseTokenizer.Mode.SEARCH;
            } else if ("normal".equalsIgnoreCase(modeSetting)) {
                mode = JapaneseTokenizer.Mode.NORMAL;
            } else if ("extended".equalsIgnoreCase(modeSetting)) {

    }

    @Override
    public void close() {
        if (httpClient == null) {
            return;
        }
        if (logger.isDebugEnabled()) {
            logger.debug("Closing HcHttpClient...");
        }
        if (connectionMonitorTask != null) {
            connectionMonitorTask.cancel();
        }
        if (httpClient != null) {
            try {
                httpClient.close();

    protected int idPrefixLength = 445;

    /**
     * Returns the FesenClient instance, connecting if not already connected.
     * @return The FesenClient instance.
     */
    protected FesenClient getClient() {
        if (!fesenClient.connected()) {
            synchronized (fesenClient) {
                if (!fesenClient.connected()) {
                    fesenClient.connect();
                }
            }

                executeCallbacks = new ArrayList<>(doneCallbacks.size());
                if (response != null) {
                    Consumer<RESPONSE> callback;
                    while ((callback = doneCallbacks.poll()) != null) {
                        executeCallbacks.add(callback);
                    }
                }
            }
            if (executeCallbacks.size() > 0) {