Lucene-6.4.2：找不到类DefaultSimilarity，尝试添加查询。

Question

我正在为我们的项目中的基于文本的搜索测试Apache lucene。 不幸的是，我在缺少库时遇到了问题。 我尝试添加lucene查询，但这没有帮助。 我究竟做错了什么？

错误日志：

Caused by: java.lang.NoClassDefFoundError: org/apache/lucene/search/similarities/DefaultSimilarity
    at org.hibernate.search.spi.SearchIntegratorBuilder.createCleanFactoryState(SearchIntegratorBuilder.java:287)
    at org.hibernate.search.spi.SearchIntegratorBuilder.buildNewSearchFactory(SearchIntegratorBuilder.java:186)
    at org.hibernate.search.spi.SearchIntegratorBuilder.buildSearchIntegrator(SearchIntegratorBuilder.java:117)
    at org.hibernate.search.hcore.impl.HibernateSearchSessionFactoryObserver.sessionFactoryCreated(HibernateSearchSessionFactoryObserver.java:66)
    at org.hibernate.internal.SessionFactoryObserverChain.sessionFactoryCreated(SessionFactoryObserverChain.java:52)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:588)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1859)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1930)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBuilder.buildSessionFactory(LocalSessionFactoryBuilder.java:372)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:454)
    at org.springframework.orm.hibernate4.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:439)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1633)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1570)
    ... 98 more
Caused by: java.lang.ClassNotFoundException: org.apache.lucene.search.similarities.DefaultSimilarity
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1858)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1701)
    ... 111 more

POM.xml：

  <!-- https://mvnrepository.com/artifact/org.apache.lucene/lucene-core -->
        <dependency>
            <groupId>org.apache.lucene</groupId>
            <artifactId>lucene-core</artifactId>
            <version>6.4.2</version>
        </dependency>

我正在尝试的代码：

  @Override
    public void saveIndexes() {
        //Apache Lucene Indexing Directory .txt files
        try {
            //indexing directory
            Path path = Paths.get("/home/akshay/index/");
            Directory directory = org.apache.lucene.store.FSDirectory.open(path);
            IndexWriterConfig config = new IndexWriterConfig(new SimpleAnalyzer());
            IndexWriter indexWriter = new IndexWriter(directory, config);
            indexWriter.deleteAll();
            File f = new File("/home/akshay/textfiles/"); // current directory
            for (File file : f.listFiles()) {
                System.out.println("indexed " + file.getCanonicalPath());
                org.apache.lucene.document.Document doc = new org.apache.lucene.document.Document();
                doc.add(new TextField("path", file.getName(), Field.Store.YES));
                FileInputStream is = new FileInputStream(file);
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                StringBuffer stringBuffer = new StringBuffer();
                String line;
                while((line = reader.readLine())!=null){
                    stringBuffer.append(line).append("\n");
                }
                reader.close();
                doc.add(new TextField("contents", stringBuffer.toString(), Field.Store.YES));
                indexWriter.addDocument(doc);
            }
            indexWriter.close();
            directory.close();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

    @Override
    public void searchLucene(String text) {
        //Apache Lucene searching text inside .txt files
        try {
            Path path = Paths.get("/home/akshay/index/");
            Directory directory = FSDirectory.open(path);
            IndexReader indexReader =  DirectoryReader.open(directory);
            IndexSearcher indexSearcher = new IndexSearcher(indexReader);
            QueryParser queryParser = new QueryParser("contents",  new StandardAnalyzer());
            Query query = queryParser.parse(text);
            TopDocs topDocs = indexSearcher.search(query,10);
            System.out.println("totalHits " + topDocs.totalHits);
            for (ScoreDoc scoreDoc : topDocs.scoreDocs) {
                org.apache.lucene.document.Document document = indexSearcher.doc(scoreDoc.doc);
                System.out.println("path " + document.get("path"));
                System.out.println("content " + document.get("contents"));
            }
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
    }

任何想法，谢谢。 :-)

Answer 1

实际上，该类已在5.4.1中弃用，在6.4.2版本中查找该类时，该类不再存在，请参见以下消息：

使用ClassicSimilarity进行同等行为，或考虑切换到BM25Similarity，这将成为Lucene 6.0中的新默认设置

见也 ：

• LUCENE-6789：IndexSearcher的默认“相似性”更改为BM25“相似性”。 使用ClassicSimilarity获取旧的向量空间DefaultSimilarity。 （罗伯特·缪尔）

将您的Lucene核心依赖项降级为5.5.4，或者在您的代码中使用ClassicSimilarity或BM25Similarity