如何使用HitCollector按字段值对Lucene结果进行排序？

public class CustomHitCollector extends TopFieldCollector {
    public CustomHitCollector(Sort sort, int numHits, int[] reverseMul) throws IOException {
        super(sort, numHits, reverseMul);
    }

    @Override
    public LeafCollector create(LeafReaderContext context, Collector in) throws IOException {
        return super.create(context, in);
    }
}

@Override
public TopDocs topDocs(int start, int howMany) throws IOException {
    return super.topDocs(start, howMany);
}

IndexSearcher searcher = new IndexSearcher(reader);
Sort sort = new Sort(new SortField("fieldName", SortField.Type.STRING));
CustomHitCollector collector = new CustomHitCollector(sort, numHits, new int[]{1});
searcher.search(query, collector);
TopDocs topDocs = collector.topDocs(start, howMany);