public abstract class

Analyzer

extends Object
implements Closeable
java.lang.Object
   ↳ org.apache.lucene.analysis.Analyzer
Known Direct Subclasses

Class Overview

An Analyzer builds TokenStreams, which analyze text. It thus represents a policy for extracting index terms from text.

Typical implementations first build a Tokenizer, which breaks the stream of characters from the Reader into raw Tokens. One or more TokenFilters may then be applied to the output of the Tokenizer.

Summary

Fields
protected boolean overridesTokenStreamMethod This field is deprecated. No replacement.
Public Constructors
Analyzer()
Public Methods
void close()
Frees persistent resources used by this Analyzer
int getOffsetGap(Fieldable field)
Just like getPositionIncrementGap(String), except for Token offsets instead.
int getPositionIncrementGap(String fieldName)
Invoked before indexing a Fieldable instance if terms have already been added to that field.
TokenStream reusableTokenStream(String fieldName, Reader reader)
Creates a TokenStream that is allowed to be re-used from the previous time that the same thread called this method.
abstract TokenStream tokenStream(String fieldName, Reader reader)
Creates a TokenStream which tokenizes all the text in the provided Reader.
Protected Methods
Object getPreviousTokenStream()
Used by Analyzers that implement reusableTokenStream to retrieve previously saved TokenStreams for re-use by the same thread.
void setOverridesTokenStreamMethod(Class<? extends Analyzer> baseClass)
This method is deprecated. This is only present to preserve back-compat of classes that subclass a core analyzer and override tokenStream but not reusableTokenStream
void setPreviousTokenStream(Object obj)
Used by Analyzers that implement reusableTokenStream to save a TokenStream for later re-use by the same thread.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.io.Closeable

Fields

protected boolean overridesTokenStreamMethod

This field is deprecated.
No replacement.

Public Constructors

public Analyzer ()

Public Methods

public void close ()

Frees persistent resources used by this Analyzer

public int getOffsetGap (Fieldable field)

Just like getPositionIncrementGap(String), except for Token offsets instead. By default this returns 1 for tokenized fields and, as if the fields were joined with an extra space character, and 0 for un-tokenized fields. This method is only called if the field produced at least one token for indexing.

Parameters
field the field just indexed
Returns

public int getPositionIncrementGap (String fieldName)

Invoked before indexing a Fieldable instance if terms have already been added to that field. This allows custom analyzers to place an automatic position increment gap between Fieldable instances using the same field name. The default value position increment gap is 0. With a 0 position increment gap and the typical default token position increment of 1, all terms in a field, including across Fieldable instances, are in successive positions, allowing exact PhraseQuery matches, for instance, across Fieldable instance boundaries.

Parameters
fieldName Fieldable name being indexed.
Returns

public TokenStream reusableTokenStream (String fieldName, Reader reader)

Creates a TokenStream that is allowed to be re-used from the previous time that the same thread called this method. Callers that do not need to use more than one TokenStream at the same time from this analyzer should use this method for better performance.

Throws
IOException

public abstract TokenStream tokenStream (String fieldName, Reader reader)

Creates a TokenStream which tokenizes all the text in the provided Reader. Must be able to handle null field name for backward compatibility.

Protected Methods

protected Object getPreviousTokenStream ()

Used by Analyzers that implement reusableTokenStream to retrieve previously saved TokenStreams for re-use by the same thread.

protected void setOverridesTokenStreamMethod (Class<? extends Analyzer> baseClass)

This method is deprecated.
This is only present to preserve back-compat of classes that subclass a core analyzer and override tokenStream but not reusableTokenStream

protected void setPreviousTokenStream (Object obj)

Used by Analyzers that implement reusableTokenStream to save a TokenStream for later re-use by the same thread.