org.apache.lucene.collation
Class ICUCollationKeyAnalyzer

java.lang.Object
  extended by org.apache.lucene.analysis.Analyzer
      extended by org.apache.lucene.collation.ICUCollationKeyAnalyzer
All Implemented Interfaces:
Closeable

public final class ICUCollationKeyAnalyzer
extends Analyzer

Configures KeywordTokenizer with ICUCollationAttributeFactory.

Converts the token into its CollationKey, and then encodes the CollationKey either directly or with IndexableBinaryStringTools (see below), 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.

You must specify the required Version compatibility when creating ICUCollationKeyAnalyzer:


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.lucene.analysis.Analyzer
Analyzer.GlobalReuseStrategy, Analyzer.PerFieldReuseStrategy, Analyzer.ReuseStrategy, Analyzer.TokenStreamComponents
 
Field Summary
 
Fields inherited from class org.apache.lucene.analysis.Analyzer
GLOBAL_REUSE_STRATEGY, PER_FIELD_REUSE_STRATEGY
 
Constructor Summary
ICUCollationKeyAnalyzer(com.ibm.icu.text.Collator collator)
          Deprecated. Use ICUCollationKeyAnalyzer(Version, Collator) and specify a version instead. This ctor will be removed in Lucene 5.0
ICUCollationKeyAnalyzer(Version matchVersion, com.ibm.icu.text.Collator collator)
          Create a new ICUCollationKeyAnalyzer, using the specified collator.
 
Method Summary
protected  Analyzer.TokenStreamComponents createComponents(String fieldName, Reader reader)
           
 
Methods inherited from class org.apache.lucene.analysis.Analyzer
close, getOffsetGap, getPositionIncrementGap, getReuseStrategy, initReader, tokenStream, tokenStream
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ICUCollationKeyAnalyzer

public ICUCollationKeyAnalyzer(Version matchVersion,
                               com.ibm.icu.text.Collator collator)
Create a new ICUCollationKeyAnalyzer, using the specified collator.

Parameters:
matchVersion - See above
collator - CollationKey generator

ICUCollationKeyAnalyzer

@Deprecated
public ICUCollationKeyAnalyzer(com.ibm.icu.text.Collator collator)
Deprecated. Use ICUCollationKeyAnalyzer(Version, Collator) and specify a version instead. This ctor will be removed in Lucene 5.0

Method Detail

createComponents

protected Analyzer.TokenStreamComponents createComponents(String fieldName,
                                                          Reader reader)
Specified by:
createComponents in class Analyzer


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