| /* |
| * 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. |
| */ |
| package org.apache.lucene.analysis.cjk; |
| |
| |
| import java.io.IOException; |
| |
| import org.apache.lucene.analysis.Analyzer; |
| import org.apache.lucene.analysis.CharArraySet; |
| import org.apache.lucene.analysis.LowerCaseFilter; |
| 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.standard.StandardTokenizer; |
| |
| /** |
| * An {@link Analyzer} that tokenizes text with {@link StandardTokenizer}, |
| * normalizes content with {@link CJKWidthFilter}, folds case with |
| * {@link LowerCaseFilter}, forms bigrams of CJK with {@link CJKBigramFilter}, |
| * and filters stopwords with {@link StopFilter} |
| * |
| * @since 3.1 |
| */ |
| public final class CJKAnalyzer extends StopwordAnalyzerBase { |
| |
| /** |
| * File containing default CJK stopwords. |
| * <p> |
| * Currently it contains some common English words that are not usually |
| * useful for searching and some double-byte interpunctions. |
| */ |
| 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 CharArraySet getDefaultStopSet(){ |
| return DefaultSetHolder.DEFAULT_STOP_SET; |
| } |
| |
| private static class DefaultSetHolder { |
| static final CharArraySet DEFAULT_STOP_SET; |
| |
| static { |
| try { |
| DEFAULT_STOP_SET = loadStopwordSet(false, CJKAnalyzer.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"); |
| } |
| } |
| } |
| |
| /** |
| * Builds an analyzer which removes words in {@link #getDefaultStopSet()}. |
| */ |
| public CJKAnalyzer() { |
| this(DefaultSetHolder.DEFAULT_STOP_SET); |
| } |
| |
| /** |
| * Builds an analyzer with the given stop words |
| * |
| * @param stopwords |
| * a stopword set |
| */ |
| public CJKAnalyzer(CharArraySet stopwords){ |
| super(stopwords); |
| } |
| |
| @Override |
| protected TokenStreamComponents createComponents(String fieldName) { |
| final Tokenizer source = new StandardTokenizer(); |
| // run the widthfilter first before bigramming, it sometimes combines characters. |
| TokenStream result = new CJKWidthFilter(source); |
| result = new LowerCaseFilter(result); |
| result = new CJKBigramFilter(result); |
| return new TokenStreamComponents(source, new StopFilter(result, stopwords)); |
| } |
| |
| @Override |
| protected TokenStream normalize(String fieldName, TokenStream in) { |
| TokenStream result = new CJKWidthFilter(in); |
| result = new LowerCaseFilter(result); |
| return result; |
| } |
| } |