Lucene 快速入门

Lucene使得全文索引这项技术活变得非常简单，我将用5分钟做个快速展示。

1.建立索引  这个例子展示的是在内存中为几个String建立索引

StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_44);Directory index = new RAMDirectory();IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_44, analyzer);IndexWriter w = new IndexWriter(index, config);addDoc(w, "Lucene in Action", "193398817");addDoc(w, "Lucene for Dummies", "55320055Z");addDoc(w, "Managing Gigabytes", "55063554A");addDoc(w, "The Art of Computer Science", "9900333X");w.close();

来看addDoc()方法：

private static void addDoc(IndexWriter w, String title, String isbn) throws IOException {  Document doc = new Document();  doc.add(new TextField("title", title, Field.Store.YES));  doc.add(new StringField("isbn", isbn, Field.Store.YES));  w.addDocument(doc);}

2.查询 从标准输入读取查询信息，建立Lucene的Query对象

String querystr = args.length > 0 ? args[0] : "lucene";Query q = new QueryParser(Version.LUCENE_44, "title", analyzer).parse(querystr);

3.查找 利用2产生的Query对象建立Searcher对象在索引中查找

int hitsPerPage = 10;IndexReader reader = IndexReader.open(index);IndexSearcher searcher = new IndexSearcher(reader);TopScoreDocCollector collector = TopScoreDocCollector.create(hitsPerPage, true);searcher.search(q, collector);ScoreDoc[] hits = collector.topDocs().scoreDocs;

4.显示 显示查找结果

System.out.println("找到 " + hits.length + " hits.");for(int i=0;i<hits.length;++i) {    int docId = hits[i].doc;    Document d = searcher.doc(docId);    System.out.println((i + 1) + ". " + d.get("isbn") + "\t" + d.get("title"));}

完整的Java代码：

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.queryparser.classic.ParseException;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.TopScoreDocCollector;import org.apache.lucene.store.Directory;import org.apache.lucene.store.RAMDirectory;import org.apache.lucene.util.Version;import java.io.IOException;public class HelloLucene {  public static void main(String[] args) throws IOException, ParseException {    // 0. analyzer     //        StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_44);    // 1. index    Directory index = new RAMDirectory();    IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_44, analyzer);    IndexWriter w = new IndexWriter(index, config);    addDoc(w, "Lucene in Action", "193398817");    addDoc(w, "Lucene for Dummies", "55320055Z");    addDoc(w, "Managing Gigabytes", "55063554A");    addDoc(w, "The Art of Computer Science", "9900333X");    w.close();    // 2. query    String querystr = args.length > 0 ? args[0] : "lucene";      Query q = new QueryParser(Version.LUCENE_44, "title", analyzer).parse(querystr);    // 3. search    int hitsPerPage = 10;    IndexReader reader = DirectoryReader.open(index);    IndexSearcher searcher = new IndexSearcher(reader);    TopScoreDocCollector collector = TopScoreDocCollector.create(hitsPerPage, true);    searcher.search(q, collector);    ScoreDoc[] hits = collector.topDocs().scoreDocs;       // 4. display     System.out.println("找到 " + hits.length + " hits.");    for(int i=0;i<hits.length;++i) {      int docId = hits[i].doc;      Document d = searcher.doc(docId);      System.out.println((i + 1) + ". " + d.get("isbn") + "\t" + d.get("title"));    }    reader.close();  }  private static void addDoc(IndexWriter w, String title, String isbn) throws IOException {    Document doc = new Document();    doc.add(new TextField("title", title, Field.Store.YES));    doc.add(new StringField("isbn", isbn, Field.Store.YES));    w.addDocument(doc);  }}