Package org.apache.lucene.analysis.icu

Class ICUCollationKeyAnalyzer

java.lang.Object
org.apache.lucene.analysis.Analyzer
org.apache.lucene.analysis.icu.ICUCollationKeyAnalyzer
All Implemented Interfaces:
Closeable, AutoCloseable
public final class ICUCollationKeyAnalyzer extends org.apache.lucene.analysis.Analyzer
Configures KeywordTokenizer with ICUCollationAttributeFactory.

Converts the token into its 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. RuleBasedCollators are independently versioned, so it is safe to search against stored CollationKeys if 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):

  1. Collator version - see Collator.getVersion()
  2. The collation strength used - see Collator.setStrength(int)

CollationKeys generated by ICU Collators are not compatible with those generated by java.text.Collators. Specifically, if you use ICUCollationKeyAnalyzer to generate index terms, do not use CollationKeyAnalyzer on the query side, or vice versa.

ICUCollationKeyAnalyzer is 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.

Since:
3.1

  • Nested Class Summary

    Nested classes/interfaces inherited from class org.apache.lucene.analysis.Analyzer

    org.apache.lucene.analysis.Analyzer.ReuseStrategy, org.apache.lucene.analysis.Analyzer.TokenStreamComponents

  • Field Summary

    Fields inherited from class org.apache.lucene.analysis.Analyzer

    GLOBAL_REUSE_STRATEGY, PER_FIELD_REUSE_STRATEGY

  • Constructor Summary

    Constructors
    Constructor
    Description
    ICUCollationKeyAnalyzer(com.ibm.icu.text.Collator collator)
    Create a new ICUCollationKeyAnalyzer, using the specified collator.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected org.apache.lucene.analysis.Analyzer.TokenStreamComponents
    createComponents(String fieldName)
     

    Methods inherited from class org.apache.lucene.analysis.Analyzer

    attributeFactory, close, getOffsetGap, getPositionIncrementGap, getReuseStrategy, initReader, initReaderForNormalization, normalize, normalize, tokenStream, tokenStream

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • ICUCollationKeyAnalyzer

      public ICUCollationKeyAnalyzer(com.ibm.icu.text.Collator collator)
      Create a new ICUCollationKeyAnalyzer, using the specified collator.
      Parameters:
      collator - CollationKey generator

  • Method Details

    • createComponents

      protected org.apache.lucene.analysis.Analyzer.TokenStreamComponents createComponents(String fieldName)
      Specified by:
      createComponents in class org.apache.lucene.analysis.Analyzer