net.sf.mmm.search.engine.impl.lucene.LuceneSearchHighlighter.java Source code

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Here is the source code for net.sf.mmm.search.engine.impl.lucene.LuceneSearchHighlighter.java

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/* Copyright (c) The m-m-m Team, Licensed under the Apache License, Version 2.0
 * http://www.apache.org/licenses/LICENSE-2.0 */
package net.sf.mmm.search.engine.impl.lucene;

import java.io.IOException;
import java.io.StringReader;

import net.sf.mmm.search.api.SearchEntry;
import net.sf.mmm.search.api.SearchException;
import net.sf.mmm.search.engine.api.SearchHit;
import net.sf.mmm.search.engine.base.SearchHighlighter;
import net.sf.mmm.util.nls.api.NlsAccess;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.highlight.Formatter;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
import org.apache.lucene.search.highlight.QueryScorer;

/**
 * This is the implementation of the {@link SearchHighlighter} interface using lucene as underlying
 * search-engine.
 *
 * @author Joerg Hohwiller (hohwille at users.sourceforge.net)
 */
public class LuceneSearchHighlighter implements SearchHighlighter {

    /** the lucene highlighter */
    private final Highlighter highlighter;

    /** the lucene analyzer */
    private final Analyzer analyzer;

    /**
     * The constructor.
     *
     * @param searchAnalyzer is the {@link Analyzer} used by the {@link LuceneSearchEngine search-engine}.
     * @param formatter is the formatter used to highlight terms.
     * @param searchQuery is the {@link Query} of the search. Matching terms of this query shall be highlighted.
     */
    public LuceneSearchHighlighter(Analyzer searchAnalyzer, Formatter formatter, Query searchQuery) {

        super();
        this.highlighter = new Highlighter(formatter, new QueryScorer(searchQuery));
        this.analyzer = searchAnalyzer;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getHighlightedText(String text) {

        String result = null;
        if (text != null) {
            try {
                // result = this.highlighter.getBestFragment(this.analyzer,
                // SearchProperties.PROPERTY_TEXT, text);

                TokenStream tokenStream = this.analyzer.tokenStream(SearchEntry.FIELD_TEXT, new StringReader(text));
                result = this.highlighter.getBestFragments(tokenStream, text, 3, SearchHit.HIGHLIGHT_CUT_TEXT);
            } catch (IOException e) {
                result = text;
            } catch (InvalidTokenOffsetsException e) {
                // TODO
                throw new SearchException(e, NlsAccess.getFactory().create(e.getMessage())) {
                };
            }
        }
        if (result == null) {
            result = "";
        }
        return result;
    }

}