TestTransformer transformer3 = new TestTransformer("transformer3");

        ResponseData responseData = new ResponseData();
        responseData.setUrl("http://example.com");

        ResultData result1 = transformer1.transform(responseData);
        ResultData result2 = transformer2.transform(responseData);
        ResultData result3 = transformer3.transform(responseData);

        TestTransformer transformer1 = new TestTransformer();
        NameTrackingTransformer transformer2 = new NameTrackingTransformer();

        transformer1.setName("transformer1");
        transformer2.setName("transformer2");

        assertEquals("transformer1", transformer1.getName());
        assertEquals("transformer2", transformer2.getName());

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

import org.codelibs.fess.crawler.transformer.Transformer;

/**
 * An abstract base class for transformers.
 * Provides basic implementation for managing the transformer's name.
 *
 */
public abstract class AbstractTransformer implements Transformer {

    /**
     * Creates a new instance of AbstractTransformer.
     */

                accessResult.setAccessResultData(null);
                try {
                    final Transformer transformer = ComponentUtil.getComponent(accessResultData.getTransformerName());
                    if (transformer == null) {
                        // no transformer
                        logger.warn("No transformer: {}", accessResultData.getTransformerName());
                        continue;
                    }

    @Override
    public Object getData(final AccessResultData<?> accessResultData) {
        // check transformer name
        if (!getName().equals(accessResultData.getTransformerName())) {
            throw new CrawlerSystemException(
                    "Transformer is invalid. Use " + accessResultData.getTransformerName() + ". This transformer is " + getName() + ".");
        }
        final byte[] data = accessResultData.getData();

fess-crawler-parent/
├── fess-crawler/              # Core crawler framework
│   ├── client/               # Protocol clients (HTTP, FTP, SMB, etc.)
│   ├── extractor/           # Content extractors
│   ├── transformer/         # Data transformers
│   └── service/             # Core services
├── fess-crawler-lasta/       # LastaFlute DI integration
└── fess-crawler-opensearch/  # OpenSearch backend
```

### Key Components

    final Multimap<K, V1> fromMultimap;
    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

    final Multimap<K, V1> fromMultimap;
    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

 * <p>
 * The {@link #getData(AccessResultData)} method allows retrieving the transformed data as a String (XML content),
 * a Map, or an instance of a specified class.
 * </p>
 *
 * <p>
 * Example usage:
 * </p>
 *
 * <pre>
 * XpathTransformer transformer = new XpathTransformer();
 * transformer.addFieldRule("title", "//title/text()");
 * transformer.addFieldRule("body", "//body/p/text()");
 *

    }

    /**
     * Gets the transformer.
     *
     * @return the transformer
     */
    public Transformer getTransformer() {
        return transformer;
    }

    /**
     * Sets the transformer.
     *
     * @param transformer the transformer to set
     */
    public void setTransformer(final Transformer transformer) {
        this.transformer = transformer;
    }

    /**