net.chwise.documents.HighlightedFragmentsRetriever.java Source code

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Here is the source code for net.chwise.documents.HighlightedFragmentsRetriever.java

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/**
 Copyright (c) 2013 Alexander Savochkin
 Chemical wikipedia search (chwise.net) web-site source code
    
 This file is part of ChWiSe.Net infrastructure.
    
 ChWiSe.Net infrastructure is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.
    
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
    
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.chwise.documents;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.highlight.*;

import java.io.IOException;

//See
//http://hrycan.com/2009/10/25/lucene-highlighter-howto/
// and
//http://code.google.com/p/hrycan-blog/source/browse/trunk/lucene-highlight/src/com/hrycan/search/HighlighterUtil.java

public class HighlightedFragmentsRetriever {

    public String[] getFragmentsWithHighlightedTerms(Analyzer analyzer, Query query, String fieldName,
            String fieldContents, int fragmentNumber, int fragmentSize)
            throws IOException, InvalidTokenOffsetsException {

        TokenStream stream = TokenSources.getTokenStream(fieldName, fieldContents, analyzer);
        QueryScorer scorer = new QueryScorer(query, fieldName);
        Fragmenter fragmenter = new SimpleSpanFragmenter(scorer, fragmentSize);

        Highlighter highlighter = new Highlighter(scorer);
        highlighter.setTextFragmenter(fragmenter);
        highlighter.setMaxDocCharsToAnalyze(Integer.MAX_VALUE);

        String[] fragments = highlighter.getBestFragments(stream, fieldContents, fragmentNumber);

        if (fragments.length == 0) {
            //Return starting piece of fieldContents fragment
            fragments = new String[1];
            fragments[0] = fieldContents.substring(0, Math.min(fragmentSize, fieldContents.length()));
        }

        return fragments;
    }

}