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Home » lucene-3.0.1-src » org.apache » lucene » analysis » [javadoc | source]
org.apache.lucene.analysis
abstract public class: Analyzer [javadoc | source]
java.lang.Object
   org.apache.lucene.analysis.Analyzer

All Implemented Interfaces:
    Closeable

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.
Field Summary
protected  boolean overridesTokenStreamMethod   
     
    Method from org.apache.lucene.analysis.Analyzer Summary:
    close,   getOffsetGap,   getPositionIncrementGap,   getPreviousTokenStream,   reusableTokenStream,   setOverridesTokenStreamMethod,   setPreviousTokenStream,   tokenStream
    Methods from java.lang.Object:
    clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
    Method from org.apache.lucene.analysis.Analyzer Detail:
     public  void close() 
      Frees persistent resources used by this Analyzer
     public int getOffsetGap(Fieldable field) 
      Just like #getPositionIncrementGap , 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.
     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.
     protected Object getPreviousTokenStream() 
      Used by Analyzers that implement reusableTokenStream to retrieve previously saved TokenStreams for re-use by the same thread.
     public TokenStream reusableTokenStream(String fieldName,
        Reader reader) throws IOException 
      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.
     protected  void setOverridesTokenStreamMethod(Class<Analyzer> baseClass) 
    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.
     abstract public 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.