Lucene_demo05_内存索引和文件索引

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本文介绍如何使用Lucene实现内存索引与文件索引的整合，包括内存索引的特点及其与文件索引的区别，并展示了如何将两者结合使用以提高效率。

[size=xx-large][color=orange][b]Lucene_demo05_内存索引和文件索引[/b][/color][/size]

[b]内存索引库:[/b]数据是临时的、访问速度比文件索引库要快、索引库中的数据不能存放太多、内存索引库和文件索引库能结合在一起
[b]两个或者两个以上的索引库的合并:[/b]
如果是内存索引库，直接调用构造函数进行合并就可以了内存索引库中。也可以调用addIndexesNoOptimize进行合并
如果是文件索引库，调用addIndexesNoOptimize进行合并，该方法可以接受多个索引库


public class RamIndex {
	/**
	 * 内存索引库
	 */
	@Test
	public void testRAM() throws Exception {
		// 创建了内存索引库
		Directory directory = new RAMDirectory();
		IndexWriter indexWriter = new IndexWriter(directory, LuceneUtils.analyzer, MaxFieldLength.LIMITED);
		Article article = new Article();
		article.setId(26L);
		article.setTitle("NBA总冠军");
		article.setContent("LBJ和韦德能带领热火在2013赛季拿到NBA总冠军吗");
		Document document = DocumentUtils.article2Document(article);
		indexWriter.addDocument(document);
		indexWriter.close();
		this.showData(directory);
	}

	/**
	 * 内存索引库和文件索引库的结合
	 */
	@Test
	public void testRamIndexAndFileIndex() throws Exception {
		Directory fileDirectory = FSDirectory.open(new File("./indexDir"));// 创建两个索引库
		Directory ramDirectory = new RAMDirectory(fileDirectory);

		// 内存索引
		IndexWriter ramIndexWriter = new IndexWriter(ramDirectory, LuceneUtils.analyzer, MaxFieldLength.LIMITED);// 这个ramIndexWriter是针对内存索引库
		Article article = new Article();
		article.setId(26L);
		article.setTitle("热火赢了总冠军");
		article.setContent("哈哈，热火终于赢了，果然不负众望！！");
		Document document = DocumentUtils.article2Document(article);
		ramIndexWriter.addDocument(document);
		ramIndexWriter.close();

		// 文件索引
		IndexWriter fileIndexWriter = new IndexWriter(fileDirectory, LuceneUtils.analyzer, true, MaxFieldLength.LIMITED);// fileIndexWriter对应的索引库是fileDirectory
		fileIndexWriter.addIndexesNoOptimize(ramDirectory);// 把内存索引库的信息写入到文件索引库addIndexesNoOptimize
		fileIndexWriter.close();

		// 经过两个索引操作后，输出最后的数据
		this.showData(fileDirectory);
	}

	/**
	 * 当应用程序启动的时候，直接和内存索引库交互，当程序快结束的时候，把内存索引库中的内容追加到文件索引库中
	 */
	@Test
	public void testRamIndexAndFileIndex2() throws Exception {
		// 内存索引
		Directory directory = new RAMDirectory();
		IndexWriter ramIndexWriter = new IndexWriter(directory, LuceneUtils.analyzer, MaxFieldLength.LIMITED);
		Article article = new Article();
		article.setId(27L);
		article.setTitle("热火赢了总冠军");
		article.setContent("哈哈，热火终于赢了，果然不负众望！！");
		Document document = DocumentUtils.article2Document(article);
		ramIndexWriter.addDocument(document);
		ramIndexWriter.close();

		// 文件索引
		Directory fileDirectory = FSDirectory.open(new File("./indexDir"));
		IndexWriter fileIndexWriter = new IndexWriter(fileDirectory, LuceneUtils.analyzer, MaxFieldLength.LIMITED);
		fileIndexWriter.addIndexesNoOptimize(directory);
		fileIndexWriter.close();

		// 经过两个索引操作后，输出最后的数据
		this.showData(fileDirectory);
	}

	// 公共输出类
	private void showData(Directory directory) throws Exception {
		IndexSearcher indexSearcher = new IndexSearcher(directory);
		QueryParser queryParser = new MultiFieldQueryParser(Version.LUCENE_30, new String[] { "title", "content" }, LuceneUtils.analyzer);
		Query query = queryParser.parse("总冠军");
		TopDocs topDocs = indexSearcher.search(query, 50);
		ScoreDoc[] scoreDocs = topDocs.scoreDocs;
		List<Article> articleList = new ArrayList<Article>();
		for (int i = 0; i < scoreDocs.length; i++) {
			Document document = indexSearcher.doc(scoreDocs[i].doc);
			Article article = DocumentUtils.document2Article(document);
			articleList.add(article);
		}

		// 输出查询出来的索引对象
		for (Article article : articleList) {
			System.out.println(article.getId());
			System.out.println(article.getTitle());
			System.out.println(article.getContent());
		}
	}
}