lucene创建索引的几种方式(一)
什么是索引：
根据你输入的值去找，这个值就是索引
第一种创建索引的方式：
根据文件来生成索引，如后缀为.txt等的文件
步骤：
第一步：FSDirectory.open(Paths.get(url));根据路径获取存储索引的目录。
FSDirectory：表示对文件系统目录的操作。RAMDirectory ：内存中的目录操作。
Paths为NIO(new io)的一个类；Path 类是 java.io.File 类的升级版，File file=newFile("index.html")而Path path=Paths.get("index.html");由于 Path 类基于字符串创建，因此它引用的资源也有可能不存在。
关于nio:传统的io流都是通过字节的移动来处理的，也就是说输入/输出流一次只能处理一个字节，因此面向流的输入/输出系统通常效率不高；因此引进了新IO(new IO),NIO采用内存映射文件的方式来处理输入/输出，NIO将文件或文件的一段区域映射到内存中，这样就可以向访问内存一样来访问文件了(这种方式模拟了操作系统上的虚拟内存的概念)，所以NIO的效率很快。
第二步：new IndexWriter(Directory,IndexWriterConfig)创建索引
第三步：索引指定目录的文件
第四步：将文件写入lucene中的文档(Document)
package com.wp.util; import java.io.File; import java.io.FileReader; import java.nio.file.Paths; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.document.Field; import org.apache.lucene.document.TextField; import org.apache.lucene.index.IndexWriter; import org.apache.lucene.index.IndexWriterConfig; import org.apache.lucene.store.Directory; import org.apache.lucene.store.FSDirectory; public class Indexer { private IndexWriter writer; // 写索引实例 /** * 构造方法 实例化IndexWriter * * @param indexDir * @throws Exception */ public Indexer(String indexDir) throws Exception { Directory dir = FSDirectory.open(Paths.get(indexDir));// 根据路径获取存储索引的目录 Analyzer analyzer = new StandardAnalyzer(); // 这里用了多态，StandardAnalyzer是标准分词器，Analyzer是一个分词器
IndexWriterConfig iwc = new IndexWriterConfig(analyzer); writer = new IndexWriter(dir, iwc); } /** * 关闭写索引 * * @throws Exception */ public void close() throws Exception { writer.close(); } /** * 索引指定目录的所有文件 * * @param dataDir * @throws Exception */ public int index(String dataDir) throws Exception { File[] files = new File(dataDir).listFiles(); for (File f : files) { indexFile(f); } return writer.numDocs(); } /** * 索引指定文件 * * @param f */ private void indexFile(File f) throws Exception { // 关于f.getCanonicalPath()查看http://www.blogjava.net/dreamstone/archive/2007/08/08/134968.html System.out.println("索引文件：" + f.getCanonicalPath()); Document doc = getDocument(f); writer.addDocument(doc); } /** * 获取文档，文档里再设置每个字段 * * @param f */ private Document getDocument(File f) throws Exception { Document doc = new Document(); doc.add(new TextField("contents", new FileReader(f))); doc.add(new TextField("fileName", f.getName(), Field.Store.YES)); doc .add(new TextField("fullPath", f.getCanonicalPath(), Field.Store.YES)); return doc; } public static void main(String[] args) { String indexDir = "D:\\lucene4"; String dataDir = "D:\\lucene4\\data"; Indexer indexer = null; int numIndexed = 0; long start = System.currentTimeMillis(); try { indexer = new Indexer(indexDir); numIndexed = indexer.index(dataDir); } catch (Exception e) { e.printStackTrace(); } finally { try { indexer.close(); } catch (Exception e) { e.printStackTrace(); } } long end = System.currentTimeMillis(); System.out.println("索引：" + numIndexed + " 个文件 花费了" + (end - start) + " 毫秒"); } }
第二种创建索引的方式：
根据字段来生成索引，我用的是数组
第一步：创建索引
第二步：将字段添加到文档中
package com.wp.util; import java.nio.file.Paths; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.document.Field; import org.apache.lucene.document.StringField; import org.apache.lucene.document.TextField; import org.apache.lucene.index.DirectoryReader; import org.apache.lucene.index.IndexReader; import org.apache.lucene.index.IndexWriter; import org.apache.lucene.index.IndexWriterConfig; import org.apache.lucene.index.Term; import org.apache.lucene.store.Directory; import org.apache.lucene.store.FSDirectory; import org.junit.Before; import org.junit.Test; public class IndexIngTest { private String ids[] = { "1", "2", "3" }; private String citys[] = { "qingdao", "nanjing", "shanghai" }; private String descs[] = { "Qingdao is a beautiful city.", "Nanjing is a city of culture.", "Shanghai is a bustling city." }; private Directory dir;// 目录 /** * 获取IndexWriter实例 * * @return * @throws Exception */ private IndexWriter getWriter() throws Exception { Analyzer analyzer = new StandardAnalyzer(); // 标准分词器 IndexWriterConfig iwc = new IndexWriterConfig(analyzer); IndexWriter writer = new IndexWriter(dir, iwc); return writer; } /** * 添加文档 * * @throws Exception */ @Before public void setUp() throws Exception { dir = FSDirectory.open(Paths.get("D:\\lucene\\luceneIndex"));// 得到luceneIndex目录 IndexWriter writer = getWriter();// 得到索引 for (int i = 0; i < ids.length; i++) { Document doc = new Document();// 创建文档 doc.add(new StringField("id", ids[i], Field.Store.YES));// 将id属性存入内存中 doc.add(new StringField("city", citys[i], Field.Store.YES)); doc.add(new TextField("desc", descs[i], Field.Store.NO)); writer.addDocument(doc); // 添加文档 } writer.close(); } /** * 测试写了几个文档 * * @throws Exception */ @Test public void testIndexWriter() throws Exception { IndexWriter writer = getWriter(); System.out.println("写入了" + writer.numDocs() + "个文档"); writer.close(); } /** * 测试读取文档 * * @throws Exception */ @Test public void testIndexReader() throws Exception { IndexReader reader = DirectoryReader.open(dir); System.out.println("最大文档数：" + reader.maxDoc()); System.out.println("实际文档数：" + reader.numDocs()); reader.close(); } /** * 测试删除 在合并前 * * @throws Exception */ @Test public void testDeleteBeforeMerge() throws Exception { IndexWriter writer = getWriter(); System.out.println("删除前：" + writer.numDocs()); writer.deleteDocuments(new Term("id", "1"));// term：根据id找到为1的 writer.commit(); System.out.println("writer.maxDoc()：" + writer.maxDoc()); System.out.println("writer.numDocs()：" + writer.numDocs()); writer.close(); } /** * 测试删除 在合并后 * * @throws Exception */ @Test public void testDeleteAfterMerge() throws Exception { IndexWriter writer = getWriter(); System.out.println("删除前：" + writer.numDocs()); writer.deleteDocuments(new Term("id", "1")); writer.forceMergeDeletes(); // 强制删除 writer.commit(); System.out.println("writer.maxDoc()：" + writer.maxDoc()); System.out.println("writer.numDocs()：" + writer.numDocs()); writer.close(); } /** * 测试更新 * * @throws Exception */ @Test public void testUpdate() throws Exception { IndexWriter writer = getWriter(); Document doc = new Document(); doc.add(new StringField("id", "1", Field.Store.YES)); doc.add(new StringField("city", "qingdao", Field.Store.YES)); doc.add(new TextField("desc", "dsss is a city.", Field.Store.NO)); writer.updateDocument(new Term("id", "1"), doc); writer.close(); } }
生成的索引文件如下：
关于索引的搜索：
这里有一个要注意的地方：一定要先创建出索引后才能去进行查找，否则会报
org.apache.lucene.index.IndexNotFoundException:
no segments* file found in MMapDirectory@D:\lucene lockFactory=org.apache.lucene.store.NativeFSLockFactory@753f67a9: files: [data, lucene-5.3.1, lucene-5.3.1.zip]
package com.wp.lucene; import java.nio.file.Paths; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.index.DirectoryReader; import org.apache.lucene.index.IndexReader; import org.apache.lucene.queryparser.classic.QueryParser; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.ScoreDoc; import org.apache.lucene.search.TopDocs; import org.apache.lucene.store.Directory; import org.apache.lucene.store.FSDirectory; public class Searcher { /** * * @param indexDir * 哪个目录 * @param q * 要查询的字段 * @throws Exception */ public static void search(String indexDir, String q) throws Exception { Directory dir = FSDirectory.open(Paths.get(indexDir));// 打开目录 IndexReader reader = DirectoryReader.open(dir);// 进行读取 IndexSearcher is = new IndexSearcher(reader);// 索引查询器 Analyzer analyzer = new StandardAnalyzer(); // 标准分词器 QueryParser parser = new QueryParser("contents", analyzer);// 在哪查询，第一个参数为查询的Document，在Indexer中创建了 Query query = parser.parse(q);// 对字段进行解析后返回给查询 long start = System.currentTimeMillis(); TopDocs hits = is.search(query, 10);// 开始查询，10代表前10条数据；返回一个文档 long end = System.currentTimeMillis(); System.out.println("匹配 " + q + " ，总共花费" + (end - start) + "毫秒" + "查询到" + hits.totalHits + "个记录"); for (ScoreDoc scoreDoc : hits.scoreDocs) { Document doc = is.doc(scoreDoc.doc);// 根据文档的标识获取文档 System.out.println(doc.get("fullPath")); } reader.close(); } /** * 执行这个main方法进行查询之前，必须要有索引，即先执行Indexer这个类 * * @param args */ public static void main(String[] args) { String indexDir = "D:\\lucene"; String q = "ADD"; try { search(indexDir, q); } catch (Exception e) { e.printStackTrace(); } } }
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