}

    /**
     * Test serialization and deserialization
     */
    public void test_serialization() throws Exception {
        // Test each enum value
        CrawlerStatus[] statuses = CrawlerStatus.values();

        for (CrawlerStatus original : statuses) {
            // Serialize
            ByteArrayOutputStream baos = new ByteArrayOutputStream();

    }

    /**
     * Retrieves an extractor for the specified key.
     * If multiple extractors are associated with the key, returns a composite extractor
     * that tries each extractor in order until one succeeds.
     *
     * @param key the key to look up
     * @return the extractor for the key, or null if not found
     */
    public Extractor getExtractor(final String key) {

 *   <li>{@link UrlQueueService} - The service for managing the URL queue.</li>
 *   <li>{@link DataService} - The service for managing access results.</li>
 * </ul>
 *
 * <p>Each parameter is stored in a ThreadLocal variable to ensure thread safety.</p>
 *
 * <p>Usage example:</p>
 * <pre>
 * {@code
 * UrlQueue<?> urlQueue = CrawlingParameterUtil.getUrlQueue();

    private StandardCrawlerContainer container;

    @Override
    protected void setUp() throws Exception {
        super.setUp();

        // Reset counters before each test
        TestComponent.resetCounter();
        SingletonTestComponent.resetInstanceCount();

        // Initialize container with test components

         * @param request the request data
         */
        void onRequestStart(FaultTolerantClient client, RequestData request);

        /**
         * Called before each request attempt.
         *
         * @param client the fault-tolerant client
         * @param request the request data
         * @param count the current retry count
         */

 * maximum thread check count, maximum depth, and maximum access count.
 * </p>
 *
 * <p>
 * It also provides thread-local storage for sitemaps, allowing each thread to have its own set of sitemaps.
 * </p>
 */
public class CrawlerContext {
    /**
     * Constructs a new CrawlerContext.
     */
    public CrawlerContext() {
        // Default constructor
    }

    @Resource
    protected MimeTypeHelper mimeTypeHelper;

    /** The HTTP client instance */
    protected volatile CloseableHttpClient httpClient;

    /** List of request headers to be sent with each request */
    private final List<Header> requestHeaderList = new ArrayList<>();

    /** Map of HTTP client properties */
    private final Map<String, Object> httpClientPropertyMap = new HashMap<>();