public final class JapaneseTokenizer extends Tokenizer
This tokenizer sets a number of additional attributes:
BaseFormAttribute containing base form for inflected
adjectives and verbs.
PartOfSpeechAttribute containing part-of-speech.
ReadingAttribute containing reading and pronunciation.
InflectionAttribute containing additional part-of-speech
information for inflected forms.
This tokenizer uses a rolling Viterbi search to find the
least cost segmentation (path) of the incoming characters.
For tokens that appear to be compound (> length 2 for all
Kanji, or > length 7 for non-Kanji), we see if there is a
2nd best segmentation of that token after applying
penalties to the long tokens. If so, and the Mode is
JapaneseTokenizer.Mode.SEARCH, we output the alternate segmentation
as well.
| Modifier and Type | Class and Description |
|---|---|
static class |
JapaneseTokenizer.Mode
Tokenization mode: this determines how the tokenizer handles
compound and unknown words.
|
AttributeSource.AttributeFactory, AttributeSource.State| Modifier and Type | Field and Description |
|---|---|
static JapaneseTokenizer.Mode |
DEFAULT_MODE
Default tokenization mode.
|
| Constructor and Description |
|---|
JapaneseTokenizer(Reader input,
UserDictionary userDictionary,
boolean discardPunctuation,
JapaneseTokenizer.Mode mode)
Create a new JapaneseTokenizer.
|
| Modifier and Type | Method and Description |
|---|---|
void |
end()
This method is called by the consumer after the last token has been
consumed, after
TokenStream.incrementToken() returned false
(using the new TokenStream API). |
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter) use this method to advance the stream to
the next token. |
void |
reset()
Resets this stream to the beginning.
|
void |
reset(Reader input)
Expert: Reset the tokenizer to a new reader.
|
void |
setGraphvizFormatter(GraphvizFormatter dotOut)
Expert: set this to produce graphviz (dot) output of
the Viterbi lattice
|
close, correctOffsetaddAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toStringpublic static final JapaneseTokenizer.Mode DEFAULT_MODE
JapaneseTokenizer.Mode.SEARCH.public JapaneseTokenizer(Reader input, UserDictionary userDictionary, boolean discardPunctuation, JapaneseTokenizer.Mode mode)
input - Reader containing textuserDictionary - Optional: if non-null, user dictionary.discardPunctuation - true if punctuation tokens should be dropped from the output.mode - tokenization mode.public void setGraphvizFormatter(GraphvizFormatter dotOut)
public void reset(Reader input) throws IOException
Tokenizerreset in class TokenizerIOExceptionpublic void reset()
throws IOException
TokenStreamTokenStream.reset() is not needed for
the standard indexing process. However, if the tokens of a
TokenStream are intended to be consumed more than once, it is
necessary to implement TokenStream.reset(). Note that if your TokenStream
caches tokens and feeds them back again after a reset, it is imperative
that you clone the tokens when you store them away (on the first pass) as
well as when you return them (on future passes after TokenStream.reset()).reset in class TokenStreamIOExceptionpublic void end()
TokenStreamTokenStream.incrementToken() returned false
(using the new TokenStream API). Streams implementing the old API
should upgrade to use this feature.
This method can be used to perform any end-of-stream operations, such as
setting the final offset of a stream. The final offset of a stream might
differ from the offset of the last token eg in case one or more whitespaces
followed after the last token, but a WhitespaceTokenizer was used.end in class TokenStreampublic boolean incrementToken()
throws IOException
TokenStreamIndexWriter) use this method to advance the stream to
the next token. Implementing classes must implement this method and update
the appropriate AttributeImpls with the attributes of the next
token.
The producer must make no assumptions about the attributes after the method
has been returned: the caller may arbitrarily change it. If the producer
needs to preserve the state for subsequent calls, it can use
AttributeSource.captureState() to create a copy of the current attribute state.
This method is called for every token of a document, so an efficient
implementation is crucial for good performance. To avoid calls to
AttributeSource.addAttribute(Class) and AttributeSource.getAttribute(Class),
references to all AttributeImpls that this stream uses should be
retrieved during instantiation.
To ensure that filters and consumers know which attributes are available,
the attributes must be added during instantiation. Filters and consumers
are not required to check for availability of attributes in
TokenStream.incrementToken().
incrementToken in class TokenStreamIOException