Java tutorial
package cc.explain.lucene; /** * 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.*; import org.apache.lucene.analysis.standard.StandardFilter; import org.apache.lucene.analysis.standard.StandardTokenizer; import org.apache.lucene.util.Version; import java.io.File; import java.io.IOException; import java.io.Reader; import java.util.Set; /** * Filters {@link org.apache.lucene.analysis.standard.StandardTokenizer} with {@link org.apache.lucene.analysis.standard.StandardFilter}, {@link * org.apache.lucene.analysis.LowerCaseFilter} and {@link org.apache.lucene.analysis.StopFilter}, using a list of * English stop words. * <p/> * <a name="version"/> * <p>You must specify the required {@link org.apache.lucene.util.Version} * compatibility when creating StandardAnalyzer: * <ul> * <li> As of 2.9, StopFilter preserves position * increments * <li> As of 2.4, Tokens incorrectly identified as acronyms * are corrected (see <a href="https://issues.apache.org/jira/browse/LUCENE-1068">LUCENE-1608</a> * </ul> */ public class StandardAnalyzerWithoutLowerCase extends Analyzer { private Set<?> stopSet; /** * Specifies whether deprecated acronyms should be replaced with HOST type. */ private final boolean replaceInvalidAcronym, enableStopPositionIncrements; /** * An unmodifiable set containing some common English words that are usually not * useful for searching. */ public static final Set<?> STOP_WORDS_SET = StopAnalyzer.ENGLISH_STOP_WORDS_SET; private final Version matchVersion; /** * Builds an analyzer with the default stop words ({@link * #STOP_WORDS_SET}). * * @param matchVersion Lucene version to match See {@link * <a href="#version">above</a>} */ public StandardAnalyzerWithoutLowerCase(Version matchVersion) { this(matchVersion, STOP_WORDS_SET); } /** * Builds an analyzer with the given stop words. * * @param matchVersion Lucene version to match See {@link * <a href="#version">above</a>} * @param stopWords stop words */ public StandardAnalyzerWithoutLowerCase(Version matchVersion, Set<?> stopWords) { stopSet = stopWords; setOverridesTokenStreamMethod(StandardAnalyzerWithoutLowerCase.class); enableStopPositionIncrements = StopFilter.getEnablePositionIncrementsVersionDefault(matchVersion); replaceInvalidAcronym = matchVersion.onOrAfter(Version.LUCENE_24); this.matchVersion = matchVersion; } /** * Builds an analyzer with the stop words from the given file. * * @param matchVersion Lucene version to match See {@link * <a href="#version">above</a>} * @param stopwords File to read stop words from * @see org.apache.lucene.analysis.WordlistLoader#getWordSet(java.io.File) */ public StandardAnalyzerWithoutLowerCase(Version matchVersion, File stopwords) throws IOException { this(matchVersion, WordlistLoader.getWordSet(stopwords)); } /** * Builds an analyzer with the stop words from the given reader. * * @param matchVersion Lucene version to match See {@link * <a href="#version">above</a>} * @param stopwords Reader to read stop words from * @see org.apache.lucene.analysis.WordlistLoader#getWordSet(java.io.Reader) */ public StandardAnalyzerWithoutLowerCase(Version matchVersion, Reader stopwords) throws IOException { this(matchVersion, WordlistLoader.getWordSet(stopwords)); } /** * Constructs a {@link org.apache.lucene.analysis.standard.StandardTokenizer} filtered by a {@link * org.apache.lucene.analysis.standard.StandardFilter}, a {@link org.apache.lucene.analysis.LowerCaseFilter} and a {@link org.apache.lucene.analysis.StopFilter}. */ @Override public TokenStream tokenStream(String fieldName, Reader reader) { StandardTokenizer tokenStream = new StandardTokenizer(matchVersion, reader); tokenStream.setMaxTokenLength(maxTokenLength); TokenStream result = new StandardFilter(tokenStream); result = new StopFilter(enableStopPositionIncrements, result, stopSet); return result; } private static final class SavedStreams { StandardTokenizer tokenStream; TokenStream filteredTokenStream; } /** * Default maximum allowed token length */ public static final int DEFAULT_MAX_TOKEN_LENGTH = 255; private int maxTokenLength = DEFAULT_MAX_TOKEN_LENGTH; /** * Set maximum allowed token length. If a token is seen * that exceeds this length then it is discarded. This * setting only takes effect the next time tokenStream or * reusableTokenStream is called. */ public void setMaxTokenLength(int length) { maxTokenLength = length; } /** * @see #setMaxTokenLength */ public int getMaxTokenLength() { return maxTokenLength; } @Override public TokenStream reusableTokenStream(String fieldName, Reader reader) throws IOException { if (overridesTokenStreamMethod) { // LUCENE-1678: force fallback to tokenStream() if we // have been subclassed and that subclass overrides // tokenStream but not reusableTokenStream return tokenStream(fieldName, reader); } SavedStreams streams = (SavedStreams) getPreviousTokenStream(); if (streams == null) { streams = new SavedStreams(); setPreviousTokenStream(streams); streams.tokenStream = new StandardTokenizer(matchVersion, reader); streams.filteredTokenStream = new StandardFilter(streams.tokenStream); streams.filteredTokenStream = new StopFilter(enableStopPositionIncrements, streams.filteredTokenStream, stopSet, true); } else { streams.tokenStream.reset(reader); } streams.tokenStream.setMaxTokenLength(maxTokenLength); streams.tokenStream.setReplaceInvalidAcronym(replaceInvalidAcronym); return streams.filteredTokenStream; } }