/* * 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.collation; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.core.KeywordTokenizer; import org.apache.lucene.util.Version; import java.text.Collator; /** *
* Configures {@link KeywordTokenizer} with {@link CollationAttributeFactory}. *
** Converts the token into its {@link java.text.CollationKey}, and then * encodes the CollationKey directly to allow * it to be stored as an index term. *
** WARNING: Make sure you use exactly the same Collator at * index and query time -- CollationKeys are only comparable when produced by * the same Collator. Since {@link java.text.RuleBasedCollator}s are not * independently versioned, it is unsafe to search against stored * CollationKeys unless the following are exactly the same (best practice is * to store this information with the index and check that they remain the * same at query time): *
*
* The ICUCollationKeyAnalyzer
in the analysis-icu package
* uses ICU4J's Collator, which makes
* its version available, thus allowing collation to be versioned
* independently from the JVM. ICUCollationKeyAnalyzer is also significantly
* faster and generates significantly shorter keys than CollationKeyAnalyzer.
* See http://site.icu-project.org/charts/collation-icu4j-sun for key
* generation timing and key length comparisons between ICU4J and
* java.text.Collator over several languages.
*
* CollationKeys generated by java.text.Collators are not compatible * with those those generated by ICU Collators. Specifically, if you use * CollationKeyAnalyzer to generate index terms, do not use * ICUCollationKeyAnalyzer on the query side, or vice versa. *
*/ public final class CollationKeyAnalyzer extends Analyzer { private final CollationAttributeFactory factory; /** * Create a new CollationKeyAnalyzer, using the specified collator. * * @param collator CollationKey generator */ public CollationKeyAnalyzer(Collator collator) { this.factory = new CollationAttributeFactory(collator); } @Override protected TokenStreamComponents createComponents(String fieldName) { KeywordTokenizer tokenizer = new KeywordTokenizer(factory, KeywordTokenizer.DEFAULT_BUFFER_SIZE); return new TokenStreamComponents(tokenizer, tokenizer); } }