在Lucene中获取搜索到的数据/元数据

Question

嗨，我是java开发人员，正在学习Lucene。我有一个用来索引pdf(lucene_in_action_2nd_edition.pdf)文件的java类和一个用来从索引中搜索一些文本的search类。IndexSearcher提供了Document，它表明字符串是否存在于索引(lucene_in_action_2nd_edition.pdf)中。

但是现在I want to get searched data or metadata. i.e. I want to know that at which page string is matched, or few text around matched string, etc...如何做到这一点呢？

下面是我的LuceneSearcher.java类：

public static void main(String[] args) throws Exception {
    File indexDir = new File("D:\\index");

    String querystr = "Advantages of FastVectorHighlighter";
    Query q = new QueryParser(Version.LUCENE_40, "contents",
            new StandardAnalyzer(Version.LUCENE_40)).parse(querystr);

    int hitsPerPage = 100;
    IndexReader reader = DirectoryReader.open(FSDirectory.open(indexDir));
    IndexSearcher searcher = new IndexSearcher(reader);
    TopScoreDocCollector collector = TopScoreDocCollector.create(
            hitsPerPage, true);
    searcher.search(q, collector);
    ScoreDoc[] hits = collector.topDocs().scoreDocs;

    System.out.println("Found " + hits.length + " hits.");
    for (int i = 0; i < hits.length; i++) {
        int docId = hits[i].doc;
        Document d = searcher.doc(docId);
        System.out.println((i + 1) + "... " + d.get("filename"));
        System.out.println("=====================================================");
        System.out.println(d.get("contents"));


    }

    // reader can only be closed when there
    // is no need to access the documents any more.
    reader.close();
}

这里d.get("contents")给出了索引时存储的.pdf文件的全文(generated by Tika)。

我想要一些关于搜索文本的信息，这样我就可以在我的网页上显示这些信息，或者正确地突出显示搜索的文本(如google搜索输出)。如何做到这一点呢？我们需要写一些逻辑吗?还是Lucene在内部写？

任何类型的帮助都将不胜感激。提前谢谢。

Answer 1

org.apache.lucene.search.highlight包提供了此功能。

例如：

SimpleHTMLFormatter htmlFormatter = new SimpleHTMLFormatter();
Highlighter highlighter = new Highlighter(htmlFormatter, new QueryScorer(query));
for (int i = 0; i < hits.length; i++) {
    int docId = hits[i].doc;
    Document d = searcher.doc(docId);
    String text = doc.get("contents");
    String bestFrag = highlighter.getBestFragment(analyzer, "contents", text);
    //output, however you like.

您还可以从荧光笔中获得最佳片段的列表，而不只是单个片段，如果您愿意，请参阅Highlighter API