Java tutorial
/* * 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 alix.lucene; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.index.IndexReader; import org.apache.lucene.search.BooleanClause; import org.apache.lucene.search.BooleanQuery; import org.apache.lucene.search.Query; import java.io.IOException; import java.io.StringReader; import java.util.Arrays; import java.util.Set; /** * A simple wrapper for MoreLikeThis for use in scenarios where a Query object * is required eg in custom QueryParser extensions. At query.rewrite() time the * reader is used to construct the actual MoreLikeThis object and obtain the * real Query object. */ public class MoreLikeThisQuery extends Query { private String likeText; private String[] moreLikeFields; private Analyzer analyzer; private final String fieldName; private float percentTermsToMatch = 0.3f; private int minTermFrequency = 1; private int maxQueryTerms = 50; private Set<?> stopWords = null; private int minDocFreq = -1; /** * @param moreLikeFields * fields used for similarity measure */ public MoreLikeThisQuery(String likeText, String[] moreLikeFields, Analyzer analyzer, String fieldName) { this.likeText = likeText; this.moreLikeFields = moreLikeFields; this.analyzer = analyzer; this.fieldName = fieldName; } @Override public Query rewrite(IndexReader reader) throws IOException { if (getBoost() != 1f) { return super.rewrite(reader); } MoreLikeThis mlt = new MoreLikeThis(reader); mlt.setFieldNames(moreLikeFields); mlt.setAnalyzer(analyzer); mlt.setMinTermFreq(minTermFrequency); if (minDocFreq >= 0) { mlt.setMinDocFreq(minDocFreq); } mlt.setMaxQueryTerms(maxQueryTerms); mlt.setStopWords(stopWords); BooleanQuery bq = (BooleanQuery) mlt.like(fieldName, new StringReader(likeText)); BooleanQuery.Builder newBq = new BooleanQuery.Builder(); newBq.setDisableCoord(bq.isCoordDisabled()); for (BooleanClause clause : bq) { newBq.add(clause); } // make at least half the terms match newBq.setMinimumNumberShouldMatch((int) (bq.clauses().size() * percentTermsToMatch)); return newBq.build(); } /* * (non-Javadoc) * * @see org.apache.lucene.search.Query#toString(java.lang.String) */ @Override public String toString(String field) { return "like:" + likeText; } public float getPercentTermsToMatch() { return percentTermsToMatch; } public void setPercentTermsToMatch(float percentTermsToMatch) { this.percentTermsToMatch = percentTermsToMatch; } public Analyzer getAnalyzer() { return analyzer; } public void setAnalyzer(Analyzer analyzer) { this.analyzer = analyzer; } public String getLikeText() { return likeText; } public void setLikeText(String likeText) { this.likeText = likeText; } public int getMaxQueryTerms() { return maxQueryTerms; } public void setMaxQueryTerms(int maxQueryTerms) { this.maxQueryTerms = maxQueryTerms; } public int getMinTermFrequency() { return minTermFrequency; } public void setMinTermFrequency(int minTermFrequency) { this.minTermFrequency = minTermFrequency; } public String[] getMoreLikeFields() { return moreLikeFields; } public void setMoreLikeFields(String[] moreLikeFields) { this.moreLikeFields = moreLikeFields; } public Set<?> getStopWords() { return stopWords; } public void setStopWords(Set<?> stopWords) { this.stopWords = stopWords; } public int getMinDocFreq() { return minDocFreq; } public void setMinDocFreq(int minDocFreq) { this.minDocFreq = minDocFreq; } @Override public int hashCode() { final int prime = 31; int result = super.hashCode(); result = prime * result + ((analyzer == null) ? 0 : analyzer.hashCode()); result = prime * result + ((fieldName == null) ? 0 : fieldName.hashCode()); result = prime * result + ((likeText == null) ? 0 : likeText.hashCode()); result = prime * result + maxQueryTerms; result = prime * result + minDocFreq; result = prime * result + minTermFrequency; result = prime * result + Arrays.hashCode(moreLikeFields); result = prime * result + Float.floatToIntBits(percentTermsToMatch); result = prime * result + ((stopWords == null) ? 0 : stopWords.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (!super.equals(obj)) return false; if (getClass() != obj.getClass()) return false; MoreLikeThisQuery other = (MoreLikeThisQuery) obj; if (analyzer == null) { if (other.analyzer != null) return false; } else if (!analyzer.equals(other.analyzer)) return false; if (fieldName == null) { if (other.fieldName != null) return false; } else if (!fieldName.equals(other.fieldName)) return false; if (likeText == null) { if (other.likeText != null) return false; } else if (!likeText.equals(other.likeText)) return false; if (maxQueryTerms != other.maxQueryTerms) return false; if (minDocFreq != other.minDocFreq) return false; if (minTermFrequency != other.minTermFrequency) return false; if (!Arrays.equals(moreLikeFields, other.moreLikeFields)) return false; if (Float.floatToIntBits(percentTermsToMatch) != Float.floatToIntBits(other.percentTermsToMatch)) return false; if (stopWords == null) { if (other.stopWords != null) return false; } else if (!stopWords.equals(other.stopWords)) return false; return true; } }