public final class JapaneseKatakanaStemFilter extends TokenFilter
TokenFilter that normalizes common katakana spelling variations
ending in a long sound character by removing this character (U+30FC). Only
katakana words longer than a minimum length are stemmed (default is four).
Note that only full-width katakana characters are supported. Please use a
CJKWidthFilter to convert half-width
katakana to full-width before using this filter.
In order to prevent terms from being stemmed, use an instance of
KeywordMarkerFilter
or a custom TokenFilter that sets the KeywordAttribute
before this TokenStream.
AttributeSource.AttributeFactory, AttributeSource.State| Modifier and Type | Field and Description |
|---|---|
static int |
DEFAULT_MINIMUM_LENGTH |
input| Constructor and Description |
|---|
JapaneseKatakanaStemFilter(TokenStream input) |
JapaneseKatakanaStemFilter(TokenStream input,
int minimumLength) |
| Modifier and Type | Method and Description |
|---|---|
boolean |
incrementToken()
Consumers (i.e.,
IndexWriter) use this method to advance the stream to
the next token. |
close, end, resetaddAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, restoreState, toStringpublic static final int DEFAULT_MINIMUM_LENGTH
public JapaneseKatakanaStemFilter(TokenStream input, int minimumLength)
public JapaneseKatakanaStemFilter(TokenStream input)
public 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