21、学习Lucene3.5索引之近实时搜索常用工具类

public class LuceneContext {
    /**
     *     将该类设置成单例模式，向外只开放轻量级的接口（诸如：IndexSearcher），
     * 重量级的变量（诸如：NRTManager、SearcherManager）全部设成私有访问权限.
     */
    private static LuceneContext luceneContext;

    private static final String PATH = "e:/lucene/index03";
    private static Analyzer analyzer;
    private static Directory directory;
    private static IndexWriter indexWriter;
    private static Version version;
    private static NRTManager nrtManager;
    private static SearcherManager searcherManager;

    private LuceneContext(){

    }
    public static LuceneContext getInstance(){
        if (luceneContext == null){
            init();
            luceneContext = new LuceneContext();
        }
        return luceneContext;
    }

    private static void init(){
        try {
            directory = FSDirectory.open(new File(PATH));
            version = Version.LUCENE_35;
            analyzer = new MMSegAnalyzer();
            indexWriter = new IndexWriter(directory, new IndexWriterConfig(version, analyzer));
            nrtManager = new NRTManager(indexWriter, Executors.newCachedThreadPool(), new SearcherWarmer() {
                @Override
                public void warm(IndexSearcher s) throws IOException {
                    System.out.println("reopen index");
                }
            });
            searcherManager = nrtManager.getSearcherManager(true);
            NRTManagerReopenThread reopenThread = new NRTManagerReopenThread(nrtManager, 5.0, 0.025);
            //设置为后台进程，进程退出，该线程就关闭
            reopenThread.setDaemon(true);
            reopenThread.setName("NRTManagerReopenThread");
            reopenThread.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取IndexSearcher
     */
    public IndexSearcher getIndexSearcher(){
        return searcherManager.acquire();
    }

    /**
     * 释放IndexSearcher
     */
    public void releaseIndexSearcher(IndexSearcher indexSearcher){
        try {
            if (indexSearcher != null){
                searcherManager.release(indexSearcher);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 提交更新后的索引
     */
    public void commitIndex(){
        try {
            indexWriter.commit();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取NRTManager（对索引的增删改查需要用到NRTManager）
     */
    public NRTManager getNRTManager(){
        return nrtManager;
    }
}