Lucene example source code file (IndexFiles.java)

This example Lucene source code file (IndexFiles.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

date, date, docs_path, document, field, field, file, file, fileinputstream, indexwriter, io, ioexception, numericfield, string, string, util

The Lucene IndexFiles.java source code

package org.apache.lucene.demo;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

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.NumericField;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
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.apache.lucene.util.Version;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Date;

/** Index all text files under a directory.
 * <p>
 * This is a command-line application demonstrating simple Lucene indexing.
 * Run it with no command-line arguments for usage information.
 */
public class IndexFiles {
  
  private IndexFiles() {}

  /** Index all text files under a directory. */
  public static void main(String[] args) {
    String usage = "java org.apache.lucene.demo.IndexFiles"
                 + " [-index INDEX_PATH] [-docs DOCS_PATH] [-update]\n\n"
                 + "This indexes the documents in DOCS_PATH, creating a Lucene index"
                 + "in INDEX_PATH that can be searched with SearchFiles";
    String indexPath = "index";
    String docsPath = null;
    boolean create = true;
    for(int i=0;i<args.length;i++) {
      if ("-index".equals(args[i])) {
        indexPath = args[i+1];
        i++;
      } else if ("-docs".equals(args[i])) {
        docsPath = args[i+1];
        i++;
      } else if ("-update".equals(args[i])) {
        create = false;
      }
    }

    if (docsPath == null) {
      System.err.println("Usage: " + usage);
      System.exit(1);
    }

    final File docDir = new File(docsPath);
    if (!docDir.exists() || !docDir.canRead()) {
      System.out.println("Document directory '" +docDir.getAbsolutePath()+ "' does not exist or is not readable, please check the path");
      System.exit(1);
    }
    
    Date start = new Date();
    try {
      System.out.println("Indexing to directory '" + indexPath + "'...");

      Directory dir = FSDirectory.open(new File(indexPath));
      Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_31);
      IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_31, analyzer);

      if (create) {
        // Create a new index in the directory, removing any
        // previously indexed documents:
        iwc.setOpenMode(OpenMode.CREATE);
      } else {
        // Add new documents to an existing index:
        iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);
      }

      // Optional: for better indexing performance, if you
      // are indexing many documents, increase the RAM
      // buffer.  But if you do this, increase the max heap
      // size to the JVM (eg add -Xmx512m or -Xmx1g):
      //
      // iwc.setRAMBufferSizeMB(256.0);

      IndexWriter writer = new IndexWriter(dir, iwc);
      indexDocs(writer, docDir);

      // NOTE: if you want to maximize search performance,
      // you can optionally call optimize here.  This can be
      // a costly operation, so generally it's only worth
      // it when your index is relatively static (ie you're
      // done adding documents to it):
      //
      // writer.optimize();

      writer.close();

      Date end = new Date();
      System.out.println(end.getTime() - start.getTime() + " total milliseconds");

    } catch (IOException e) {
      System.out.println(" caught a " + e.getClass() +
       "\n with message: " + e.getMessage());
    }
  }

  /**
   * Indexes the given file using the given writer, or if a directory is given,
   * recurses over files and directories found under the given directory.
   * 
   * NOTE: This method indexes one document per input file.  This is slow.  For good
   * throughput, put multiple documents into your input file(s).  An example of this is
   * in the benchmark module, which can create "line doc" files, one document per line,
   * using the
   * <a href="../../../../../contrib-benchmark/org/apache/lucene/benchmark/byTask/tasks/WriteLineDocTask.html"
   * >WriteLineDocTask</a>.
   *  
   * @param writer Writer to the index where the given file/dir info will be stored
   * @param file The file to index, or the directory to recurse into to find files to index
   * @throws IOException
   */
  static void indexDocs(IndexWriter writer, File file)
    throws IOException {
    // do not try to index files that cannot be read
    if (file.canRead()) {
      if (file.isDirectory()) {
        String[] files = file.list();
        // an IO error could occur
        if (files != null) {
          for (int i = 0; i < files.length; i++) {
            indexDocs(writer, new File(file, files[i]));
          }
        }
      } else {

        FileInputStream fis;
        try {
          fis = new FileInputStream(file);
        } catch (FileNotFoundException fnfe) {
          // at least on windows, some temporary files raise this exception with an "access denied" message
          // checking if the file can be read doesn't help
          return;
        }

        try {

          // make a new, empty document
          Document doc = new Document();

          // Add the path of the file as a field named "path".  Use a
          // field that is indexed (i.e. searchable), but don't tokenize 
          // the field into separate words and don't index term frequency
          // or positional information:
          Field pathField = new Field("path", file.getPath(), Field.Store.YES, Field.Index.NOT_ANALYZED_NO_NORMS);
          pathField.setOmitTermFreqAndPositions(true);
          doc.add(pathField);

          // Add the last modified date of the file a field named "modified".
          // Use a NumericField that is indexed (i.e. efficiently filterable with
          // NumericRangeFilter).  This indexes to milli-second resolution, which
          // is often too fine.  You could instead create a number based on
          // year/month/day/hour/minutes/seconds, down the resolution you require.
          // For example the long value 2011021714 would mean
          // February 17, 2011, 2-3 PM.
          NumericField modifiedField = new NumericField("modified");
          modifiedField.setLongValue(file.lastModified());
          doc.add(modifiedField);

          // Add the contents of the file to a field named "contents".  Specify a Reader,
          // so that the text of the file is tokenized and indexed, but not stored.
          // Note that FileReader expects the file to be in UTF-8 encoding.
          // If that's not the case searching for special characters will fail.
          doc.add(new Field("contents", new BufferedReader(new InputStreamReader(fis, "UTF-8"))));

          if (writer.getConfig().getOpenMode() == OpenMode.CREATE) {
            // New index, so we just add the document (no old document can be there):
            System.out.println("adding " + file);
            writer.addDocument(doc);
          } else {
            // Existing index (an old copy of this document may have been indexed) so 
            // we use updateDocument instead to replace the old one matching the exact 
            // path, if present:
            System.out.println("updating " + file);
            writer.updateDocument(new Term("path", file.getPath()), doc);
          }
          
        } finally {
          fis.close();
        }
      }
    }
  }
}