public final class CollationKeyAnalyzer extends AnalyzerConfigures
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. Since
RuleBasedCollators 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):
- JVM vendor
- JVM version, including patch version
- The language (and country and variant, if specified) of the Locale used when constructing
the collator via
- The collation strength used - see
ICUCollationKeyAnalyzerin 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.
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
Methods inherited from class org.apache.lucene.analysis.Analyzer
close, getOffsetGap, getPositionIncrementGap, getReuseStrategy, initReader, initReaderForNormalization, normalize, normalize, tokenStream, tokenStream
public CollationKeyAnalyzer(Collator collator)Create a new CollationKeyAnalyzer, using the specified collator.
collator- CollationKey generator