摘要：序說(shuō)是界的檢索之王，當(dāng)之無(wú)愧。近年來(lái)的火爆登場(chǎng)，包括之前的及，其底層都是。簡(jiǎn)單了解，對(duì)使用還是有點(diǎn)幫助的。是當(dāng)前最流行的開(kāi)源大數(shù)據(jù)內(nèi)存計(jì)算框架，采用語(yǔ)言實(shí)現(xiàn)，由伯克利大學(xué)實(shí)驗(yàn)室開(kāi)發(fā)并于年開(kāi)源。

說(shuō)lucene是Java界的檢索之王，當(dāng)之無(wú)愧。近年來(lái)elasticsearch的火爆登場(chǎng)，包括之前的solr及solr cloud，其底層都是lucene。簡(jiǎn)單了解lucene，對(duì)使用elasticsearch還是有點(diǎn)幫助的。本文就簡(jiǎn)單過(guò)一下其簡(jiǎn)單的api使用。

        
            org.apache.lucene
            lucene-core
            4.6.1
        
        
            org.apache.lucene
            lucene-analyzers-common
            4.6.1
        
        
            org.apache.lucene
            lucene-queryparser
            4.6.1
        
        
            org.apache.lucene
            lucene-codecs
            4.6.1
        

File indexDir = new File(this.getClass().getClassLoader().getResource("").getFile());

    @Test
    public void createIndex() throws IOException {
//        Directory index = new RAMDirectory();
        Directory index = FSDirectory.open(indexDir);
        // 0. Specify the analyzer for tokenizing text.
        //    The same analyzer should be used for indexing and searching
        StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_46);
        IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_46, analyzer);

        // 1. create the index
        IndexWriter w = new IndexWriter(index, config);
        addDoc(w, "Lucene in Action", "193398817");
        addDoc(w, "Lucene for Dummies", "55320055Z");
        addDoc(w, "Managing Gigabytes", "55063554A");
        addDoc(w, "The Art of Computer Science", "9900333X");
        w.close();
    }

    private void addDoc(IndexWriter w, String title, String isbn) throws IOException {
        Document doc = new Document();
        doc.add(new TextField("title", title, Field.Store.YES));
        // use a string field for isbn because we don"t want it tokenized
        doc.add(new StringField("isbn", isbn, Field.Store.YES));
        w.addDocument(doc);
    }

 @Test
    public void search() throws IOException {
        // 2. query
        String querystr = "lucene";

        // the "title" arg specifies the default field to use
        // when no field is explicitly specified in the query.
        Query q = null;
        try {
            StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_46);
            q = new QueryParser(Version.LUCENE_46,"title", analyzer).parse(querystr);
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 3. search
        int hitsPerPage = 10;
        Directory index = FSDirectory.open(indexDir);
        IndexReader reader = DirectoryReader.open(index);
        IndexSearcher searcher = new IndexSearcher(reader);
        TopScoreDocCollector collector = TopScoreDocCollector.create(hitsPerPage, true);
        searcher.search(q, collector);
        ScoreDoc[] hits = collector.topDocs().scoreDocs;

        // 4. display results
        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("isbn") + "	" + d.get("title"));
        }

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

對(duì)于搜索來(lái)說(shuō)，分詞出現(xiàn)在兩個(gè)地方，一個(gè)是對(duì)用戶輸入的關(guān)鍵詞進(jìn)行分詞，另一個(gè)是在索引文檔時(shí)對(duì)文檔內(nèi)容的分詞。兩個(gè)分詞最好一樣，這樣才可以更好地匹配出來(lái)。

    @Test
    public void cutWords() throws IOException {
//        StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_46);
//        CJKAnalyzer analyzer = new CJKAnalyzer(Version.LUCENE_46);
        SimpleAnalyzer analyzer = new SimpleAnalyzer();
        String text = "Spark是當(dāng)前最流行的開(kāi)源大數(shù)據(jù)內(nèi)存計(jì)算框架，采用Scala語(yǔ)言實(shí)現(xiàn)，由UC伯克利大學(xué)AMPLab實(shí)驗(yàn)室開(kāi)發(fā)并于2010年開(kāi)源。";
        TokenStream tokenStream = analyzer.tokenStream("content", new StringReader(text));
        CharTermAttribute charTermAttribute = tokenStream.addAttribute(CharTermAttribute.class);
        try {
            tokenStream.reset();
            while (tokenStream.incrementToken()) {
                System.out.println(charTermAttribute.toString());
            }
            tokenStream.end();
        } finally {
            tokenStream.close();
            analyzer.close();
        }
    }

輸出

spark
是
當(dāng)前
最
流行
的
開(kāi)源
大數(shù)
據(jù)
內(nèi)存
計(jì)算
框架
采用
scala
語(yǔ)言
實(shí)現(xiàn)
由
uc
伯克利
大學(xué)
amplab
實(shí)驗(yàn)室
開(kāi)發(fā)
并于
2010
年
開(kāi)源

本工程github

lucenetutorial

helloLucene