* </pre>
 */
public class Crawler {

    /**
     * Creates a new instance of Crawler.
     */
    public Crawler() {
        // Default constructor
    }

    /** Logger instance for this class. */
    private static final Logger logger = LogManager.getLogger(Crawler.class);

    /** Thread name for web and file system crawling process. */

 *
 * <p>Example usage:
 * <pre>
 *   Crawler crawler = new Crawler();
 *   crawler.addUrl("http://example.com/");
 *   crawler.execute();
 *   crawler.close();
 * </pre>
 */
public class Crawler implements Runnable, AutoCloseable {

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

    /**
     * Service for managing URL queues during crawling.
     */

### Key File Locations

**Core**: `fess-crawler/src/main/java/org/codelibs/fess/crawler/`
- `Crawler.java`, `CrawlerContext.java`, `CrawlerThread.java`

**Clients**: `fess-crawler/src/main/java/org/codelibs/fess/crawler/client/`
- `http/HcHttpClient.java`, `fs/FileSystemClient.java`, `storage/StorageClient.java`

**DI Config**: `fess-crawler-lasta/src/main/resources/crawler.xml`

### Exception Hierarchy

```

import org.codelibs.fess.Constants;
import org.codelibs.fess.crawler.builder.RequestDataBuilder;
import org.codelibs.fess.crawler.client.CrawlerClient;
import org.codelibs.fess.crawler.client.CrawlerClientFactory;
import org.codelibs.fess.crawler.entity.RequestData;
import org.codelibs.fess.crawler.entity.ResponseData;
import org.codelibs.fess.crawler.entity.ResultData;
import org.codelibs.fess.crawler.exception.ChildUrlsException;

import org.codelibs.fess.Constants;
import org.codelibs.fess.crawler.Crawler;
import org.codelibs.fess.crawler.entity.AccessResult;
import org.codelibs.fess.crawler.entity.AccessResultData;
import org.codelibs.fess.crawler.entity.OpenSearchAccessResult;
import org.codelibs.fess.crawler.entity.OpenSearchUrlQueue;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlFilterService;

        assertFalse(robotsTxt.allows("/aaa", "Crawler"));
        assertTrue(robotsTxt.allows("/bbb", "Crawler"));
        assertTrue(robotsTxt.allows("/ccc", "Crawler"));
        assertTrue(robotsTxt.allows("/ddd", "Crawler"));
        assertTrue(robotsTxt.allows("/aaa", "Crawler/1.0"));
        assertFalse(robotsTxt.allows("/bbb", "Crawler/1.0"));
        assertTrue(robotsTxt.allows("/ccc", "Crawler/1.0"));

        this.componentName = componentName;
    }

    /**
     * Gets the crawler container.
     *
     * @return The crawler container
     */
    public CrawlerContainer getCrawlerContainer() {
        return crawlerContainer;
    }

    /**
     * Sets the crawler container.
     *
     * @param crawlerContainer The crawler container to set
     */

import org.codelibs.fess.crawler.entity.ExtractData;
import org.codelibs.fess.crawler.exception.ExtractException;
import org.codelibs.fess.crawler.exception.MaxLengthExceededException;
import org.codelibs.fess.crawler.extractor.Extractor;
import org.codelibs.fess.crawler.extractor.ExtractorFactory;
import org.codelibs.fess.crawler.helper.MimeTypeHelper;
import org.codelibs.fess.crawler.util.IgnoreCloseInputStream;

import org.codelibs.fess.crawler.entity.ExtractData;
import org.codelibs.fess.crawler.exception.ExtractException;
import org.codelibs.fess.crawler.exception.MaxLengthExceededException;
import org.codelibs.fess.crawler.extractor.Extractor;
import org.codelibs.fess.crawler.extractor.ExtractorFactory;
import org.codelibs.fess.crawler.helper.MimeTypeHelper;
import org.codelibs.fess.crawler.util.IgnoreCloseInputStream;

 */
package org.codelibs.fess.crawler.extractor.impl;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;

import org.codelibs.fess.crawler.container.CrawlerContainer;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;
import org.codelibs.fess.crawler.extractor.Extractor;
import org.codelibs.fess.crawler.extractor.ExtractorFactory;