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Lucene example source code file (RussianAnalyzer.java)

This example Lucene source code file (RussianAnalyzer.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

default_stop_set, deprecated, deprecated, io, keywordmarkerfilter, lowercasefilter, russiananalyzer, russiananalyzer, set, set, stopfilter, string, string, tokenizer, tokenstreamcomponents, util

The Lucene RussianAnalyzer.java source code

package org.apache.lucene.analysis.ru;

/**
 * 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 java.io.IOException;
import java.io.Reader;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.LowerCaseFilter;
import org.apache.lucene.analysis.snowball.SnowballFilter;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.analysis.KeywordMarkerFilter;
import org.apache.lucene.analysis.StopFilter;
import org.apache.lucene.analysis.StopwordAnalyzerBase;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.WordlistLoader;
import org.apache.lucene.util.Version;

/**
 * {@link Analyzer} for Russian language. 
 * <p>
 * Supports an external list of stopwords (words that
 * will not be indexed at all).
 * A default set of stopwords is used unless an alternative list is specified.
 * </p>
 * <a name="version"/>
 * <p>You must specify the required {@link Version}
 * compatibility when creating RussianAnalyzer:
 * <ul>
 *   <li> As of 3.1, StandardTokenizer is used, Snowball stemming is done with
 *        SnowballFilter, and Snowball stopwords are used by default.
 * </ul>
 */
public final class RussianAnalyzer extends StopwordAnalyzerBase
{
    /**
     * List of typical Russian stopwords. (for backwards compatibility)
     * @deprecated Remove this for LUCENE 5.0
     */
    @Deprecated
    private static final String[] RUSSIAN_STOP_WORDS_30 = {
      "а", "без", "более", "бы", "был", "была", "были", "было", "быть", "в",
      "вам", "вас", "весь", "во", "вот", "все", "всего", "всех", "вы", "где", 
      "да", "даже", "для", "до", "его", "ее", "ей", "ею", "если", "есть", 
      "еще", "же", "за", "здесь", "и", "из", "или", "им", "их", "к", "как",
      "ко", "когда", "кто", "ли", "либо", "мне", "может", "мы", "на", "надо", 
      "наш", "не", "него", "нее", "нет", "ни", "них", "но", "ну", "о", "об", 
      "однако", "он", "она", "они", "оно", "от", "очень", "по", "под", "при", 
      "с", "со", "так", "также", "такой", "там", "те", "тем", "то", "того", 
      "тоже", "той", "только", "том", "ты", "у", "уже", "хотя", "чего", "чей", 
      "чем", "что", "чтобы", "чье", "чья", "эта", "эти", "это", "я"
    };
    
    /** File containing default Russian stopwords. */
    public final static String DEFAULT_STOPWORD_FILE = "russian_stop.txt";
    
    private static class DefaultSetHolder {
      /** @deprecated remove this for Lucene 5.0 */
      @Deprecated
      static final Set<?> DEFAULT_STOP_SET_30 = CharArraySet
          .unmodifiableSet(new CharArraySet(Version.LUCENE_CURRENT, 
              Arrays.asList(RUSSIAN_STOP_WORDS_30), false));
      static final Set<?> DEFAULT_STOP_SET;
      
      static {
        try {
          DEFAULT_STOP_SET = 
            WordlistLoader.getSnowballWordSet(SnowballFilter.class, DEFAULT_STOPWORD_FILE);
        } catch (IOException ex) {
          // default set should always be present as it is part of the
          // distribution (JAR)
          throw new RuntimeException("Unable to load default stopword set");
        }
      }
    }
    
    private final Set<?> stemExclusionSet;
    
    /**
     * Returns an unmodifiable instance of the default stop-words set.
     * 
     * @return an unmodifiable instance of the default stop-words set.
     */
    public static Set<?> getDefaultStopSet() {
      return DefaultSetHolder.DEFAULT_STOP_SET;
    }

    public RussianAnalyzer(Version matchVersion) {
      this(matchVersion,
        matchVersion.onOrAfter(Version.LUCENE_31) ? DefaultSetHolder.DEFAULT_STOP_SET
            : DefaultSetHolder.DEFAULT_STOP_SET_30);
    }
  
    /**
     * Builds an analyzer with the given stop words.
     * @deprecated use {@link #RussianAnalyzer(Version, Set)} instead
     */
    @Deprecated
    public RussianAnalyzer(Version matchVersion, String... stopwords) {
      this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
    }
    
    /**
     * Builds an analyzer with the given stop words
     * 
     * @param matchVersion
     *          lucene compatibility version
     * @param stopwords
     *          a stopword set
     */
    public RussianAnalyzer(Version matchVersion, Set<?> stopwords){
      this(matchVersion, stopwords, CharArraySet.EMPTY_SET);
    }
    
    /**
     * Builds an analyzer with the given stop words
     * 
     * @param matchVersion
     *          lucene compatibility version
     * @param stopwords
     *          a stopword set
     * @param stemExclusionSet a set of words not to be stemmed
     */
    public RussianAnalyzer(Version matchVersion, Set<?> stopwords, Set stemExclusionSet){
      super(matchVersion, stopwords);
      this.stemExclusionSet = CharArraySet.unmodifiableSet(CharArraySet.copy(matchVersion, stemExclusionSet));
    }
   
   
    /**
     * Builds an analyzer with the given stop words.
     * TODO: create a Set version of this ctor
     * @deprecated use {@link #RussianAnalyzer(Version, Set)} instead
     */
    @Deprecated
    public RussianAnalyzer(Version matchVersion, Map<?,?> stopwords)
    {
      this(matchVersion, stopwords.keySet());
    }

  /**
   * Creates
   * {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
   * used to tokenize all the text in the provided {@link Reader}.
   * 
   * @return {@link org.apache.lucene.analysis.ReusableAnalyzerBase.TokenStreamComponents}
   *         built from a {@link StandardTokenizer} filtered with
   *         {@link StandardFilter}, {@link LowerCaseFilter}, {@link StopFilter}
   *         , {@link KeywordMarkerFilter} if a stem exclusion set is
   *         provided, and {@link SnowballFilter}
   */
    @Override
    protected TokenStreamComponents createComponents(String fieldName,
        Reader reader) {
      if (matchVersion.onOrAfter(Version.LUCENE_31)) {
        final Tokenizer source = new StandardTokenizer(matchVersion, reader);
        TokenStream result = new StandardFilter(matchVersion, source);
        result = new LowerCaseFilter(matchVersion, result);
        result = new StopFilter(matchVersion, result, stopwords);
        if (!stemExclusionSet.isEmpty()) result = new KeywordMarkerFilter(
            result, stemExclusionSet);
        result = new SnowballFilter(result, new org.tartarus.snowball.ext.RussianStemmer());
        return new TokenStreamComponents(source, result);
      } else {
        final Tokenizer source = new RussianLetterTokenizer(matchVersion, reader);
        TokenStream result = new LowerCaseFilter(matchVersion, source);
        result = new StopFilter(matchVersion, result, stopwords);
        if (!stemExclusionSet.isEmpty()) result = new KeywordMarkerFilter(
          result, stemExclusionSet);
        return new TokenStreamComponents(source, new RussianStemFilter(result));
      }
    }
}

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