org.apache.lucene.collation
Class CollationKeyAnalyzer
java.lang.Object
org.apache.lucene.analysis.Analyzer
org.apache.lucene.collation.CollationKeyAnalyzer
public class CollationKeyAnalyzer
- extends org.apache.lucene.analysis.Analyzer
Filters KeywordTokenizer
with CollationKeyFilter
.
Converts the 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):
- JVM vendor
- JVM version, including patch version
-
The language (and country and variant, if specified) of the Locale
used when constructing the collator via
Collator.getInstance(java.util.Locale)
.
-
The collation strength used - see
Collator.setStrength(int)
ICUCollationKeyAnalyzer
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.
Fields inherited from class org.apache.lucene.analysis.Analyzer |
overridesTokenStreamMethod |
Methods inherited from class org.apache.lucene.analysis.Analyzer |
close, getOffsetGap, getPositionIncrementGap, getPreviousTokenStream, setOverridesTokenStreamMethod, setPreviousTokenStream |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
CollationKeyAnalyzer
public CollationKeyAnalyzer(Collator collator)
tokenStream
public org.apache.lucene.analysis.TokenStream tokenStream(String fieldName,
Reader reader)
- Specified by:
tokenStream
in class org.apache.lucene.analysis.Analyzer
reusableTokenStream
public org.apache.lucene.analysis.TokenStream reusableTokenStream(String fieldName,
Reader reader)
throws IOException
- Overrides:
reusableTokenStream
in class org.apache.lucene.analysis.Analyzer
- Throws:
IOException
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