org.apache.lucene.analysis.ja

Class JapaneseTokenizerFactory

java.lang.Object

org.apache.lucene.analysis.util.AbstractAnalysisFactory

org.apache.lucene.analysis.util.TokenizerFactory

org.apache.lucene.analysis.ja.JapaneseTokenizerFactory

All Implemented Interfaces:

ResourceLoaderAware

public class JapaneseTokenizerFactory
extends TokenizerFactory
implements ResourceLoaderAware

Factory for JapaneseTokenizer.

 <fieldType name="text_ja" class="solr.TextField">
   <analyzer>
     <tokenizer class="solr.JapaneseTokenizerFactory"
       mode="NORMAL"
       userDictionary="user.txt"
       userDictionaryEncoding="UTF-8"
       discardPunctuation="true"
       discardCompoundToken="false"
     />
     <filter class="solr.JapaneseBaseFormFilterFactory"/>
   </analyzer>
 </fieldType>
 

Additional expert user parameters nBestCost and nBestExamples can be used to include additional searchable tokens that those most likely according to the statistical model. A typical use-case for this is to improve recall and make segmentation more resilient to mistakes. The feature can also be used to get a decompounding effect.

The nBestCost parameter specifies an additional Viterbi cost, and when used, JapaneseTokenizer will include all tokens in Viterbi paths that are within the nBestCost value of the best path.

Finding a good value for nBestCost can be difficult to do by hand. The nBestExamples parameter can be used to find an nBestCost value based on examples with desired segmentation outcomes.

For example, a value of /箱根山-箱根/成田空港-成田/ indicates that in the texts, 箱根山 (Mt. Hakone) and 成田空港 (Narita Airport) we'd like a cost that gives is us 箱根 (Hakone) and 成田 (Narita). Notice that costs are estimated for each example individually, and the maximum nBestCost found across all examples is used.

If both nBestCost and nBestExamples is used in a configuration, the largest value of the two is used.

Parameters nBestCost and nBestExamples work with all tokenizer modes, but it makes the most sense to use them with NORMAL mode.

Since:

3.6.0

SPI Name (Note: This is case-insensitive. e.g., if the name is 'htmlStrip', 'htmlstrip' can be used when looking up the service):

"japanese"

Field Summary

Fields

Modifier and Type	Field and Description
static String	NAME SPI name

Fields inherited from class org.apache.lucene.analysis.util.AbstractAnalysisFactory

LUCENE_MATCH_VERSION_PARAM, luceneMatchVersion

Constructor Summary

Constructors

Constructor and Description
JapaneseTokenizerFactory(Map<String,String> args) Creates a new JapaneseTokenizerFactory

Method Summary

Modifier and Type	Method and Description
JapaneseTokenizer	create(AttributeFactory factory)
void	inform(ResourceLoader loader)

Methods inherited from class org.apache.lucene.analysis.util.TokenizerFactory

availableTokenizers, create, findSPIName, forName, lookupClass, reloadTokenizers

Methods inherited from class org.apache.lucene.analysis.util.AbstractAnalysisFactory

get, get, get, get, get, getBoolean, getChar, getClassArg, getFloat, getInt, getLines, getLuceneMatchVersion, getOriginalArgs, getPattern, getSet, getSnowballWordSet, getWordSet, isExplicitLuceneMatchVersion, require, require, require, requireBoolean, requireChar, requireFloat, requireInt, setExplicitLuceneMatchVersion, splitAt, splitFileNames

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NAME

public static final String NAME

SPI name

See Also:

Constant Field Values

Constructor Detail

JapaneseTokenizerFactory

public JapaneseTokenizerFactory(Map<String,String> args)

Creates a new JapaneseTokenizerFactory

Method Detail

inform

public void inform(ResourceLoader loader)
            throws IOException

Specified by:

inform in interface ResourceLoaderAware

Throws:

IOException

create

public JapaneseTokenizer create(AttributeFactory factory)

Specified by:

create in class TokenizerFactory