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From Chris Male <gento...@gmail.com>
Subject Re: Lucene 4.0 PerFieldAnalyzerWrapper question
Date Wed, 26 Sep 2012 00:17:38 GMT
Hi Mike,

I don't really understand what problem you're having.

PerFieldAnalyzerWrapper, like all AnalyzerWrappers, uses
Analyzer.PerFieldReuseStrategy which means it caches the
TokenStreamComponents per field.  The TokenStreamComponents cached are
created by by retrieving the wrapped Analyzer through
AnalyzerWrapper.getWrappedAnalyzer(Field) and calling createComponents.  In
PerFieldAnalyzerWrapper, getWrappedAnalyzer pulls the Analyzer from the Map
you provide.

Consequently to use your custom Analyzers and KeywordAnalyzer, all you need
to do is define your custom Analyzer using the new Analyzer API (that is
using TokenStreamComponents), create your Map from that Analyzer and
KeywordAnalyzer and pass it into PerFieldAnalyzerWrapper.  This seems to be
what you're doing in your code sample.

Are you able to expand on the problem you're encountering?

On Wed, Sep 26, 2012 at 11:57 AM, Mike O'Leary <tmoleary@uw.edu> wrote:

> I am updating an analyzer that uses a particular configuration of the
> PerFieldAnalyzerWrapper to work with Lucene 4.0. A few of the fields use a
> custom analyzer and StandardTokenizer and the other fields use the
> KeywordAnalyzer and KeywordTokenizer. The older version of the analyzer
> looks like this:
>
> public class MyPerFieldAnalyzer extends Analyzer {
>   PerFieldAnalyzerWrapper _analyzer;
>
>   public MyPerFieldAnalyzer() {
>     Map<String, Analyzer> analyzerMap = new HashMap<String, Analyzer>();
>
>     analyzerMap.put("IDNumber", new KeywordAnalyzer());
>     ...
>     ...
>
>     _analyzer = new PerFieldAnalyzerWrapper(new CustomAnalyzer(),
> analyzerMap);
>   }
>
>   @Override
>   public TokenStream tokenStream(String fieldname, Reader reader) {
>     TokenStream stream = _analyzer.tokenStream(fieldname, reader);
>     return stream;
>   }
> }
>
> In older versions of Lucene it is necessary to define a tokenStream
> function, but in 4.0 it is not (in fact, TokenStream is declared final, so
> you can't). Instead, it is necessary to define a createComponents function
> that takes the same arguments as the tokenStream function and returns a
> TokenStreamComponents object. The TokenStreamComponents constructor has a
> Tokenizer argument and a TokenStream argument. I assume I can just use the
> same code to provide the TokenStream object as was used in the older
> analyzer's tokenStream function, but I don't see how to provide a Tokenizer
> object, unless it is by creating a separate map of field names to
> Tokenizers that works the same way the analyzer map does. Is that the best
> way to do this, or is there a better way? For example, would it be better
> to inherit from AnalyzerWrapper instead of from Analyzer? In that case I
> would need to define getWrappedAnalyzer and wrappedComponents functions. I
> think in that case I would still need to put the same kind of logic in the
> wrapComponents function that specifies which tokenizer to use with which
> field, though. It looks like the PerFieldAnalyzerWrapper itself assumes
> that the same tokenizer will be used with all fields, as its wrapComponents
> function ignores the fieldname parameter. I would appreciate any help in
> finding out the best way to update this analyzer and to write the required
> function(s).

Thanks,
> Mike
>



-- 
Chris Male | Open Source Search Developer | elasticsearch |
www.e<http://www.dutchworks.nl>
lasticsearch.com

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