Lucene example source code file (BrazilianAnalyzer.java)

This example Lucene source code file (BrazilianAnalyzer.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

braziliananalyzer, braziliananalyzer, default_stop_set, default_stopword_file, deprecated, deprecated, file, io, ioexception, map, set, set, string, string, tokenstreamcomponents, util

The Lucene BrazilianAnalyzer.java source code

package org.apache.lucene.analysis.br;

/**
 * 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.File;
import java.io.IOException;
import java.io.Reader;
import java.util.Collections;
import java.util.HashSet;
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.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.analysis.standard.StandardAnalyzer;
import org.apache.lucene.analysis.standard.StandardFilter;
import org.apache.lucene.analysis.standard.StandardTokenizer;
import org.apache.lucene.util.Version;

/**
 * {@link Analyzer} for Brazilian Portuguese language. 
 * <p>
 * Supports an external list of stopwords (words that
 * will not be indexed at all) and an external list of exclusions (words that will
 * not be stemmed, but indexed).
 * </p>
 *
 * <p>NOTE: This class uses the same {@link Version}
 * dependent settings as {@link StandardAnalyzer}.</p>
 */
public final class BrazilianAnalyzer extends StopwordAnalyzerBase {

	/**
	 * List of typical Brazilian Portuguese stopwords.
	 * @deprecated use {@link #getDefaultStopSet()} instead
	 */
	@Deprecated
	public final static String[] BRAZILIAN_STOP_WORDS = {
      "a","ainda","alem","ambas","ambos","antes",
      "ao","aonde","aos","apos","aquele","aqueles",
      "as","assim","com","como","contra","contudo",
      "cuja","cujas","cujo","cujos","da","das","de",
      "dela","dele","deles","demais","depois","desde",
      "desta","deste","dispoe","dispoem","diversa",
      "diversas","diversos","do","dos","durante","e",
      "ela","elas","ele","eles","em","entao","entre",
      "essa","essas","esse","esses","esta","estas",
      "este","estes","ha","isso","isto","logo","mais",
      "mas","mediante","menos","mesma","mesmas","mesmo",
      "mesmos","na","nas","nao","nas","nem","nesse","neste",
      "nos","o","os","ou","outra","outras","outro","outros",
      "pelas","pelas","pelo","pelos","perante","pois","por",
      "porque","portanto","proprio","propios","quais","qual",
      "qualquer","quando","quanto","que","quem","quer","se",
      "seja","sem","sendo","seu","seus","sob","sobre","sua",
      "suas","tal","tambem","teu","teus","toda","todas","todo",
      "todos","tua","tuas","tudo","um","uma","umas","uns"};

  /** File containing default Brazilian Portuguese stopwords. */
  public final static String DEFAULT_STOPWORD_FILE = "stopwords.txt";
  
	/**
   * 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;
  }
  
  private static class DefaultSetHolder {
    static final Set<?> DEFAULT_STOP_SET;
    
    static {
      try {
        DEFAULT_STOP_SET = CharArraySet.unmodifiableSet(new CharArraySet(
            Version.LUCENE_CURRENT, WordlistLoader.getWordSet(BrazilianAnalyzer.class, 
                DEFAULT_STOPWORD_FILE, "#"), false));
      } 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");
      }
    }
  }


	/**
	 * Contains words that should be indexed but not stemmed.
	 */
	// TODO make this private in 3.1
	private Set<?> excltable = Collections.emptySet();
	
	/**
	 * Builds an analyzer with the default stop words ({@link #getDefaultStopSet()}).
	 */
	public BrazilianAnalyzer(Version matchVersion) {
    this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET);
	}
	
	/**
   * Builds an analyzer with the given stop words
   * 
   * @param matchVersion
   *          lucene compatibility version
   * @param stopwords
   *          a stopword set
   */
  public BrazilianAnalyzer(Version matchVersion, Set<?> stopwords) {
     super(matchVersion, stopwords);
  }

  /**
   * Builds an analyzer with the given stop words and stemming exclusion words
   * 
   * @param matchVersion
   *          lucene compatibility version
   * @param stopwords
   *          a stopword set
   */
  public BrazilianAnalyzer(Version matchVersion, Set<?> stopwords,
      Set<?> stemExclusionSet) {
    this(matchVersion, stopwords);
    excltable = CharArraySet.unmodifiableSet(CharArraySet
        .copy(matchVersion, stemExclusionSet));
  }

	/**
	 * Builds an analyzer with the given stop words.
	 * @deprecated use {@link #BrazilianAnalyzer(Version, Set)} instead
	 */
  @Deprecated
  public BrazilianAnalyzer(Version matchVersion, String... stopwords) {
    this(matchVersion, StopFilter.makeStopSet(matchVersion, stopwords));
  }

  /**
   * Builds an analyzer with the given stop words. 
   * @deprecated use {@link #BrazilianAnalyzer(Version, Set)} instead
   */
  @Deprecated
  public BrazilianAnalyzer(Version matchVersion, Map<?,?> stopwords) {
    this(matchVersion, stopwords.keySet());
  }

  /**
   * Builds an analyzer with the given stop words.
   * @deprecated use {@link #BrazilianAnalyzer(Version, Set)} instead
   */
  @Deprecated
  public BrazilianAnalyzer(Version matchVersion, File stopwords)
      throws IOException {
    this(matchVersion, WordlistLoader.getWordSet(stopwords));
  }

	/**
	 * Builds an exclusionlist from an array of Strings.
	 * @deprecated use {@link #BrazilianAnalyzer(Version, Set, Set)} instead
	 */
	@Deprecated
	public void setStemExclusionTable( String... exclusionlist ) {
		excltable = StopFilter.makeStopSet( matchVersion, exclusionlist );
		setPreviousTokenStream(null); // force a new stemmer to be created
	}
	/**
	 * Builds an exclusionlist from a {@link Map}.
	 * @deprecated use {@link #BrazilianAnalyzer(Version, Set, Set)} instead
	 */
	@Deprecated
	public void setStemExclusionTable( Map<?,?> exclusionlist ) {
		excltable = new HashSet<Object>(exclusionlist.keySet());
		setPreviousTokenStream(null); // force a new stemmer to be created
	}
	/**
	 * Builds an exclusionlist from the words contained in the given file.
	 * @deprecated use {@link #BrazilianAnalyzer(Version, Set, Set)} instead
	 */
	@Deprecated
	public void setStemExclusionTable( File exclusionlist ) throws IOException {
		excltable = WordlistLoader.getWordSet( exclusionlist );
		setPreviousTokenStream(null); // force a new stemmer to be created
	}

  /**
   * 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 LowerCaseFilter}, {@link StandardFilter}, {@link StopFilter}
   *         , and {@link BrazilianStemFilter}.
   */
  @Override
  protected TokenStreamComponents createComponents(String fieldName,
      Reader reader) {
    Tokenizer source = new StandardTokenizer(matchVersion, reader);
    TokenStream result = new LowerCaseFilter(matchVersion, source);
    result = new StandardFilter(matchVersion, result);
    result = new StopFilter(matchVersion, result, stopwords);
    if(excltable != null && !excltable.isEmpty())
      result = new KeywordMarkerFilter(result, excltable);
    return new TokenStreamComponents(source, new BrazilianStemFilter(result));
  }
}