* </p>
 *
 * <pre>
 * {@code
 * FtpClient ftpClient = new FtpClient();
 * ftpClient.init(); // Initialize with configured parameters
 * ResponseData responseData = ftpClient.doGet("ftp://example.com/path/to/file.txt");
 * // Process the responseData
 * ftpClient.close(); // Close and release resources
 * }
 * </pre>
 *
 * @author shinsuke
 */
public class FtpClient extends AbstractCrawlerClient {

		instance="prototype">
		<property name="charset">"UTF-8"</property>
		<!-- ntlmPasswordAuthentication -->
	</component>

	<component name="ftpClient"
		class="org.codelibs.fess.crawler.client.ftp.FtpClient" instance="prototype">
		<property name="charset">"UTF-8"</property>
	</component>

	<component name="storageClient"

Pattern-based client selection (from `crawler/client.xml`):
- `http:.*`, `https:.*` → SwitchableHttpClient
- `file:.*` → FileSystemClient
- `smb:.*` → SmbClient (SMB2+), `smb1:.*` → SmbClient (SMB1)
- `ftp:.*`, `ftps:.*` → FtpClient
- `storage:.*` → StorageClient, `s3:.*` → S3Client, `gcs:.*` → GcsClient

### Cloud Storage Clients

- **S3Client**: AWS SDK v2, `s3://bucket/path`, properties: `endpoint`, `accessKey`, `secretKey`, `region`

- **CrawlerThread**: Individual crawler thread implementation

#### Client Architecture
- **HcHttpClient**: HTTP/HTTPS client using Apache HttpComponents
- **FileSystemClient**: File system access
- **FtpClient**: FTP protocol support
- **SmbClient**: SMB/CIFS network shares
- **StorageClient**: Cloud storage integration

#### Content Processing Pipeline
- **Extractors**: Content extraction from various formats

            final String owner = (String) responseData.getMetaDataMap().get(FtpClient.FTP_FILE_USER);
            if (owner != null) {
                roleTypeList.add(systemHelper.getSearchRoleByUser(owner));
            }
            final String group = (String) responseData.getMetaDataMap().get(FtpClient.FTP_FILE_GROUP);
            if (group != null) {

import org.codelibs.fess.Constants;
import org.codelibs.fess.crawler.client.CrawlerClientFactory;
import org.codelibs.fess.crawler.client.ftp.FtpAuthentication;
import org.codelibs.fess.crawler.client.ftp.FtpClient;
import org.codelibs.fess.crawler.client.http.HcHttpClient;
import org.codelibs.fess.crawler.client.http.config.CredentialsConfig;
import org.codelibs.fess.crawler.client.http.config.CredentialsConfig.CredentialsType;