Lucene学习之CURD

创建索引

　　Lucene在进行创建索引时，根据前面一篇博客，已经讲完了大体的流程，这里再简单说下：

 Directory directory = FSDirectory.open("/tmp/testindex");
 IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_CURRENT, analyzer);
 IndexWriter iwriter = new IndexWriter(directory, config);
 Document doc = new Document();
 String text = "This is the text to be indexed.";
 doc.add(new Field("fieldname", text, TextField.TYPE_STORED)); iwriter.close();

    1 创建Directory，获取索引目录

　　2 创建词法分析器，创建IndexWriter对象

　　3 创建document对象，存储数据

　　4 关闭IndexWriter，提交

 /**
      * 建立索引
      *
      * @param args
      */
     public static void index() throws Exception {

         String text1 = "hello,man!";
         String text2 = "goodbye,man!";
         String text3 = "hello,woman!";
         String text4 = "goodbye,woman!";

         Date date1 = new Date();
         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
         directory = FSDirectory.open(new File(INDEX_DIR));

         IndexWriterConfig config = new IndexWriterConfig(
                 Version.LUCENE_CURRENT, analyzer);
         indexWriter = new IndexWriter(directory, config);

         Document doc1 = new Document();
         doc1.add(new TextField("filename", "text1", Store.YES));
         doc1.add(new TextField("content", text1, Store.YES));
         indexWriter.addDocument(doc1);

         Document doc2 = new Document();
         doc2.add(new TextField("filename", "text2", Store.YES));
         doc2.add(new TextField("content", text2, Store.YES));
         indexWriter.addDocument(doc2);

         Document doc3 = new Document();
         doc3.add(new TextField("filename", "text3", Store.YES));
         doc3.add(new TextField("content", text3, Store.YES));
         indexWriter.addDocument(doc3);

         Document doc4 = new Document();
         doc4.add(new TextField("filename", "text4", Store.YES));
         doc4.add(new TextField("content", text4, Store.YES));
         indexWriter.addDocument(doc4);

         indexWriter.commit();
         indexWriter.close();

         Date date2 = new Date();
         System.out.println("创建索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
     }

增量添加索引

　　Lucene拥有增量添加索引的功能，在不会影响之前的索引情况下，添加索引，它会在何时的时机，自动合并索引文件。

 /**
      * 增加索引
      *
      * @throws Exception
      */
     public static void insert() throws Exception {
         String text5 = "hello,goodbye,man,woman";
         Date date1 = new Date();
         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
         directory = FSDirectory.open(new File(INDEX_DIR));

         IndexWriterConfig config = new IndexWriterConfig(
                 Version.LUCENE_CURRENT, analyzer);
         indexWriter = new IndexWriter(directory, config);

         Document doc1 = new Document();
         doc1.add(new TextField("filename", "text5", Store.YES));
         doc1.add(new TextField("content", text5, Store.YES));
         indexWriter.addDocument(doc1);

         indexWriter.commit();
         indexWriter.close();

         Date date2 = new Date();
         System.out.println("增加索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
     }

删除索引

　　Lucene也是通过IndexWriter调用它的delete方法，来删除索引。我们可以通过关键字，删除与这个关键字有关的所有内容。如果仅仅是想要删除一个文档，那么最好就顶一个唯一的ID域，通过这个ID域，来进行删除操作。

 /**
      * 删除索引
      *
      * @param str 删除的关键字
      * @throws Exception
      */
     public static void delete(String str) throws Exception {
         Date date1 = new Date();
         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
         directory = FSDirectory.open(new File(INDEX_DIR));

         IndexWriterConfig config = new IndexWriterConfig(
                 Version.LUCENE_CURRENT, analyzer);
         indexWriter = new IndexWriter(directory, config);

         indexWriter.deleteDocuments(new Term("filename",str));  

         indexWriter.close();

         Date date2 = new Date();
         System.out.println("删除索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
     }

更新索引

　　Lucene没有真正的更新操作，通过某个fieldname，可以更新这个域对应的索引，但是实质上，它是先删除索引，再重新建立的。

 /**
      * 更新索引
      *
      * @throws Exception
      */
     public static void update() throws Exception {
         String text1 = "update,hello,man!";
         Date date1 = new Date();
          analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
          directory = FSDirectory.open(new File(INDEX_DIR));

          IndexWriterConfig config = new IndexWriterConfig(
                  Version.LUCENE_CURRENT, analyzer);
          indexWriter = new IndexWriter(directory, config);

          Document doc1 = new Document();
         doc1.add(new TextField("filename", "text1", Store.YES));
         doc1.add(new TextField("content", text1, Store.YES));

         indexWriter.updateDocument(new Term("filename","text1"), doc1);

          indexWriter.close();

          Date date2 = new Date();
          System.out.println("更新索引耗时：" + (date2.getTime() - date1.getTime()) + "ms\n");
     }

通过索引查询关键字

　　Lucene的查询方式有很多种，这里就不做详细介绍了。它会返回一个ScoreDoc的集合，类似ResultSet的集合，我们可以通过域名获取想要获取的内容。

 /**
      * 关键字查询
      *
      * @param str
      * @throws Exception
      */
     public static void search(String str) throws Exception {
         directory = FSDirectory.open(new File(INDEX_DIR));
         analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
         DirectoryReader ireader = DirectoryReader.open(directory);
         IndexSearcher isearcher = new IndexSearcher(ireader);

         QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "content",analyzer);
         Query query = parser.parse(str);

         ScoreDoc[] hits = isearcher.search(query, null, 1000).scoreDocs;
         for (int i = 0; i < hits.length; i++) {
             Document hitDoc = isearcher.doc(hits[i].doc);
             System.out.println(hitDoc.get("filename"));
             System.out.println(hitDoc.get("content"));
         }
         ireader.close();
         directory.close();
     }