如何从Lucene中的FeatureField中读取单个功能的值？

import org.apache.lucene.document.Document;
import org.apache.lucene.index.*;
import org.apache.lucene.search.*;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.BytesRef;

import java.io.IOException;
import java.nio.file.Paths;

public class FeatureFieldReader {
    public static void main(String[] args) throws IOException {
        String indexPath = "path/to/index";
        String featureFieldName = "featureField";

        Directory directory = FSDirectory.open(Paths.get(indexPath));
        IndexReader indexReader = DirectoryReader.open(directory);
        IndexSearcher indexSearcher = new IndexSearcher(indexReader);

        QueryParser queryParser = new QueryParser("content", new StandardAnalyzer());
        Query query = queryParser.parse("your_query_string");

        TopDocs topDocs = indexSearcher.search(query, 10);
        ScoreDoc[] scoreDocs = topDocs.scoreDocs;

        for (ScoreDoc scoreDoc : scoreDocs) {
            int docId = scoreDoc.doc;
            Document document = indexReader.document(docId);

            IndexReaderContext context = indexReader.getContext();
            LeafReaderContext leafContext = context.leaves().get(ReaderUtil.subIndex(docId, context.leaves()));
            LeafReader leafReader = leafContext.reader();

            NumericDocValues featureFieldValues = leafReader.getNumericDocValues(featureFieldName);
            if (featureFieldValues != null && featureFieldValues.advanceExact(docId)) {
                long featureValue = featureFieldValues.longValue();
                System.out.println("Feature value: " + featureValue);
            }
        }

        indexReader.close();
        directory.close();
    }
}