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java.lang.Object org.apache.lucene.util.AttributeSource.AttributeFactory org.apache.lucene.collation.CollationAttributeFactory
public class CollationAttributeFactory
Converts each token into its CollationKey
, and then
encodes the bytes 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)
The ICUCollationAttributeFactory
in the analysis-icu package
uses ICU4J's Collator, which makes its
version available, thus allowing collation to be versioned independently
from the JVM. ICUCollationAttributeFactory is also significantly faster and
generates significantly shorter keys than CollationAttributeFactory. 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 CollationAttributeFactory to generate index terms, do not use ICUCollationAttributeFactory on the query side, or vice versa.
Field Summary |
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Fields inherited from class org.apache.lucene.util.AttributeSource.AttributeFactory |
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DEFAULT_ATTRIBUTE_FACTORY |
Constructor Summary | |
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CollationAttributeFactory(AttributeSource.AttributeFactory delegate,
Collator collator)
Create a CollationAttributeFactory, using the supplied Attribute Factory as the factory for all other attributes. |
|
CollationAttributeFactory(Collator collator)
Create a CollationAttributeFactory, using AttributeSource.AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY as the
factory for all other attributes. |
Method Summary | |
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AttributeImpl |
createAttributeInstance(Class<? extends Attribute> attClass)
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Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public CollationAttributeFactory(Collator collator)
AttributeSource.AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY
as the
factory for all other attributes.
collator
- CollationKey generatorpublic CollationAttributeFactory(AttributeSource.AttributeFactory delegate, Collator collator)
delegate
- Attribute Factorycollator
- CollationKey generatorMethod Detail |
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public AttributeImpl createAttributeInstance(Class<? extends Attribute> attClass)
createAttributeInstance
in class AttributeSource.AttributeFactory
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