lucene

Posted 2020-10-09 wheleetcode

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1 全文检索工具，方便实现全文检索功能。

2 全文检索，先对要搜索的文档进行分词，形成索引，根据索引经行检索。

3 全文检索流程

索引流程：采集数据，处理数据，创建索引

搜索流程：输入查询条件，Lucene查询器查询索引，索引库取出结果

4 IndexWriter是索引过程的核心组件，通过IndexWriter可以创建新索引、更新索引、删除索引操作。IndexWriter需要通过Directory对索引进行存储操作。

Directory描述了索引的存储位置，底层封装了I/O操作，负责对索引进行存储。它是一个抽象类，它的子类常用的包括FSDirectory（在文件系统存储索引）、RAMDirectory（在内存存储索引）。

public class IndexManager {

    @Test
    public void createIndex() throws Exception {
        BookDao bookDao = new BookDaoImpl();
        List<Book> books = bookDao.queryBooks();
        List<Document> documents = new ArrayList<>();
        
        Document document = null;
        for (Book book : books) {
            document = new Document();
            Field id = new TextField("id", book.getId().toString(), Store.YES);
            Field name = new TextField("name", book.getName(), Store.YES);
            Field price = new TextField("price", book.getPrice().toString(), Store.YES);
            Field detail = new TextField("detail", book.getDetail(), Store.YES);
            document.add(id);
            document.add(name);
            document.add(price);
            document.add(detail);
            documents.add(document);
        }
        
        Analyzer analyzer = new StandardAnalyzer();
        IndexWriter indexWriter = null;
        IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_4_10_3, analyzer);
        Directory directory = FSDirectory.open(new File("E:\\\\index\\\\"));
        indexWriter = new IndexWriter(directory, config);
        
        for (Document d : documents) {
            indexWriter.addDocument(d);
        }
        indexWriter.close();
    }
}

View Code

5 搜索输入语法 and or not 大写

    public void indexSearch() throws Exception {
        QueryParser queryParser = new QueryParser("detail", new StandardAnalyzer());
        Query query = queryParser.parse("detail:好 AND 大");
        Directory directory = FSDirectory.open(new File("E:\\\\index\\\\"));
        IndexReader indexReader = DirectoryReader.open(directory);
        IndexSearcher searcher = new IndexSearcher(indexReader);
        TopDocs docs = searcher.search(query, 10);
        ScoreDoc[] scoreDocs = docs.scoreDocs;
        for (ScoreDoc scoreDoc : scoreDocs) {
            int docId = scoreDoc.doc;
            Document document = searcher.doc(docId);
            System.out.println(document.get("id"));
            System.out.println(document.get("name"));
            System.out.println(document.get("detail"));
        }
        indexReader.close();
    }

View Code

5 field 属性

1 是否分词 tokenized 分词为了索引，（商品名称，描述，价格），不分词也可以索引（商品id）

2 是否索引ndexed

3 是否存储 stored 是否将field存到文档域中，存储目的显示。名称，价格，id，图片地址

@Test
    public void createIndex() throws Exception {
        BookDao bookDao = new BookDaoImpl();
        List<Book> books = bookDao.queryBooks();
        List<Document> documents = new ArrayList<>();
        
        Document document = null;
        for (Book book : books) {
            document = new Document();
            Field id = new StringField("id", book.getId().toString(), Store.YES);
            Field name = new TextField("name", book.getName(), Store.YES);
            Field price = new FloatField("price", book.getPrice(), Store.YES);
            Field detail = new TextField("detail", book.getDetail(), Store.NO);
            document.add(id);
            document.add(name);
            document.add(price);
            document.add(detail);
            documents.add(document);
        }
        
        Analyzer analyzer = new StandardAnalyzer();
        IndexWriter indexWriter = null;
        IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_4_10_3, analyzer);
        Directory directory = FSDirectory.open(new File("E:\\\\index\\\\"));
        indexWriter = new IndexWriter(directory, config);
        
        for (Document d : documents) {
            indexWriter.addDocument(d);
        }
        indexWriter.close();
    }
}

View Code

6 修改索引

    @Test
    public void updateIndex() throws Exception {
        Analyzer analyzer = new StandardAnalyzer();
        IndexWriter indexWriter = null;
        IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_4_10_3, analyzer);
        Directory directory = FSDirectory.open(new File("E:\\\\index\\\\"));
        indexWriter = new IndexWriter(directory, config);
        Document document = new Document();
        document.add(new TextField("name", "fdrr", Store.YES));
        indexWriter.updateDocument(new Term("name", "fddd"), document);
        indexWriter.close();
    }