**Strategy**: `CrawlerClient`, `Extractor`, `Transformer` - pluggable implementations
**Builder**: `RequestDataBuilder`, `ExtractorBuilder` - fluent construction
**Template Method**: `AbstractCrawlerClient`, `AbstractExtractor` - common logic with overrides
**DI**: LastaFlute container with `@Resource` and XML config

### Core Principles

**Thread Safety**:
- `AtomicLong` for counters (`CrawlerContext.accessCount`)

import com.google.common.base.Charsets;

import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;

/**
 * Extract a text by using external http server.
 */
public class ApiExtractor extends AbstractExtractor {

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

    /** The URL of the API endpoint. */
    protected String url;

    /** The access timeout in seconds. */

 *   <li>Quoted field handling</li>
 *   <li>Column names as metadata</li>
 *   <li>Configurable encoding and row limits</li>
 * </ul>
 */
public class CsvExtractor extends AbstractExtractor {
    /** Logger instance for this class. */
    private static final Logger logger = LogManager.getLogger(CsvExtractor.class);

    /** Default encoding for CSV files. */
    protected String encoding = Constants.UTF_8;

import jakarta.mail.internet.MimeMessage;
import jakarta.mail.internet.MimeUtility;

/**
 * Gets a text from .eml file.
 *
 * @author shinsuke
 *
 */
public class EmlExtractor extends AbstractExtractor {
    /** Array of day of week abbreviations used for parsing received dates */
    private static final String[] DAY_OF_WEEK = { "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };

    /** Logger instance for this class */

import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;

/**
 * Extracts text content from various document formats using JODConverter.
 */
public class JodExtractor extends AbstractExtractor {
    /** Logger for this class. */
    private static final Logger logger = LogManager.getLogger(JodExtractor.class);

    /** Office manager for document conversion. */
    protected OfficeManager officeManager;

import org.codelibs.fess.crawler.exception.ExtractException;

/**
 * Extracts text content by executing an external command.
 */
public class CommandExtractor extends AbstractExtractor {
    private static final Logger logger = LogManager.getLogger(CommandExtractor.class);

    /** The encoding for the output. */
    protected String outputEncoding = Constants.UTF_8;

}

// Wait for completion
crawler.awaitTermination();
System.out.println("Crawling completed");
```

### Custom Content Extractor

```java
public class CustomExtractor extends AbstractExtractor {
    @Override
    public ExtractData getText(final InputStream inputStream, final Map<String, String> params) {
        // Custom extraction logic
        ExtractData extractData = new ExtractData();