论坛 › apache › apache lucene 一个最简单的实例

df3 发表于 2015-8-4 13:27:25

apache lucene 一个最简单的实例

就像每个程序都有一个Hello World来让人体验它一样，lucene也可以很简单的提供一个实例。如下（来自lucene in action的例子）有两个类组成：
一个是建立索引

package my;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Date;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;

public class Indexer {
    public static void main(String[] args) throws Exception {
      if (args.length != 2) {
            throw new Exception("Usage: java " + Indexer.class.getName()
                  + "");
      }
      File indexDir = new File(args);
      File dataDir = new File(args);
      long start = new Date().getTime();
      int numIndexed = index(indexDir, dataDir);
      long end = new Date().getTime();
      System.out.println("Indexing " + numIndexed + " files took "
                + (end - start) + " milliseconds");
    }

    // open an index and start file directory traversal
    public static int index(File indexDir, File dataDir) throws IOException {
      if (!dataDir.exists() || !dataDir.isDirectory()) {
            throw new IOException(dataDir
                  + " does not exist or is not a directory");
      }
      IndexWriter writer = new IndexWriter(indexDir, new StandardAnalyzer(),
                true);
      writer.setUseCompoundFile(false);
      indexDirectory(writer, dataDir);
      int numIndexed = writer.docCount();
      writer.optimize();
      writer.close();
      return numIndexed;
    }

    // recursive method that calls itself when it finds a directory
    private static void indexDirectory(IndexWriter writer, File dir)
            throws IOException {
      File[] files = dir.listFiles();
      for (int i = 0; i < files.length; i++) {
            File f = files;
            if (f.isDirectory()) {
                indexDirectory(writer, f);
            } else if (f.getName().endsWith(".txt")) {
                indexFile(writer, f);
            }
      }
    }

    // method to actually index file using Lucene
    private static void indexFile(IndexWriter writer, File f)
            throws IOException {
      if (f.isHidden() || !f.exists() || !f.canRead()) {
            return;
      }
      System.out.println("Indexing " + f.getCanonicalPath());
      Document doc = new Document();
      doc.add(Field.Text("contents", new FileReader(f)));
      doc.add(Field.Keyword("filename", f.getCanonicalPath()));
      writer.addDocument(doc);
    }
}另一个是搜索：

package my;

import java.io.File;
import java.util.Date;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Hits;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

public class Searcher {
    public static void main(String[] args) throws Exception {
      if (args.length != 2) {
            throw new Exception("Usage: java " + Searcher.class.getName()
                  + "");
      }
      File indexDir = new File(args);
      String q = args;
      if (!indexDir.exists() || !indexDir.isDirectory()) {
            throw new Exception(indexDir
                  + " does not exist or is not a directory.");
      }
      search(indexDir, q);
    }

    public static void search(File indexDir, String q) throws Exception {
      Directory fsDir = FSDirectory.getDirectory(indexDir, false);
      IndexSearcher is = new IndexSearcher(fsDir);
      Query query = QueryParser.parse(q, "contents", new StandardAnalyzer());
      long start = new Date().getTime();
      Hits hits = is.search(query);
      long end = new Date().getTime();
      System.err.println("Found " + hits.length() + " document(s) (in "
                + (end - start) + " milliseconds) that matched query ‘" + q
                + "’:");
      for (int i = 0; i < hits.length(); i++) {
            Document doc = hits.doc(i);
            System.out.println(doc.get("filename"));
      }
    }
}ok，这样就简单实现了，在搜索目录下所有txt，找出包括某一个字符串的txt文件名的功能。
下篇文章将介绍一下lucene的核心类

查看完整版本: apache lucene 一个最简单的实例