public final class CollationKeyFilter
extends org.apache.lucene.analysis.TokenFilter
Converts each token into its CollationKey
, and then
encodes the CollationKey with IndexableBinaryStringTools
, 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 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):
Collator.getInstance(java.util.Locale)
.
Collator.setStrength(int)
ICUCollationKeyFilter
uses ICU4J's Collator, which makes its
version available, thus allowing collation to be versioned independently
from the JVM. ICUCollationKeyFilter is also significantly faster and
generates significantly shorter keys than CollationKeyFilter. 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
CollationKeyFilter to generate index terms, do not use
ICUCollationKeyFilter
on the query side, or vice versa.
Constructor and Description |
---|
CollationKeyFilter(org.apache.lucene.analysis.TokenStream input,
java.text.Collator collator) |
Modifier and Type | Method and Description |
---|---|
boolean |
incrementToken() |
getOnlyUseNewAPI, next, next, setOnlyUseNewAPI
addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString
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