Java tutorial
/* +-----------------------------------------------------------------------------+ | ILIAS open source | +-----------------------------------------------------------------------------+ | Copyright (c) 1998-2001 ILIAS open source, University of Cologne | | | | This program 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 2 | | 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, write to the Free Software | | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | +-----------------------------------------------------------------------------+ */ package de.ilias.services.lucene.search.highlight; import java.io.IOException; import java.io.StringReader; import java.sql.SQLException; import org.apache.log4j.Logger; import org.apache.lucene.analysis.TokenStream; import org.apache.lucene.analysis.standard.StandardAnalyzer; import org.apache.lucene.document.Document; import org.apache.lucene.document.Field; import org.apache.lucene.index.CorruptIndexException; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.ScoreDoc; import org.apache.lucene.search.highlight.Fragmenter; import org.apache.lucene.search.highlight.Highlighter; import org.apache.lucene.search.highlight.QueryScorer; import org.apache.lucene.search.highlight.SimpleFragmenter; import org.apache.lucene.search.highlight.SimpleHTMLFormatter; import de.ilias.services.lucene.index.FieldInfo; import de.ilias.services.lucene.search.SearchHolder; import de.ilias.services.lucene.settings.LuceneSettings; import de.ilias.services.settings.ConfigurationException; import de.ilias.services.settings.LocalSettings; /** * * * @author Stefan Meyer <smeyer.ilias@gmx.de> * @version $Id$ */ public class HitHighlighter { private static int FRAGMENT_TITLE_SIZE = 10000; private static String HIGHLIGHT_SEPARATOR = "..."; private static String HIGHLIGHT_BEGIN_TAG = "<span class=\"ilSearchHighlight\">"; private static String HIGHLIGHT_END_TAG = "</span>"; protected static Logger logger = Logger.getLogger(HitHighlighter.class); private IndexSearcher searcher; private Query query; private ScoreDoc[] hits; private Highlighter highlighter; private Highlighter titleHighlighter; private FieldInfo fieldInfo; private HighlightHits result; private LuceneSettings luceneSettings; /** * @throws IOException * @throws ConfigurationException * @throws SQLException * */ public HitHighlighter(Query query, ScoreDoc[] hits) throws ConfigurationException, IOException, SQLException { this.query = query; this.hits = hits; init(); } /** * @throws IOException * @throws CorruptIndexException * */ public void highlight() throws CorruptIndexException, IOException { result = new HighlightHits(); HighlightObject resObject; HighlightItem resItem; HighlightField resField; TokenStream token; String fragment; String[] fields = fieldInfo.getFieldsAsStringArray(); for (int i = 0; i < hits.length; i++) { // first score is max score if (i == 0) { result.setMaxScore(hits[i].score); } StringBuffer allContent = new StringBuffer(); Document hitDoc = searcher.doc(hits[i].doc); int objId; int subItem; // Add result object try { objId = Integer.parseInt(hitDoc.get("objId")); } catch (NumberFormatException e) { logger.warn("Found invalid document with title " + hitDoc.get("title")); continue; } try { subItem = Integer.parseInt(hitDoc.get("subItem")); } catch (NumberFormatException e) { subItem = 0; } resObject = result.initObject(objId); resItem = resObject.addItem(subItem); resItem.setAbsoluteScore(hits[i].score); // Title if (hitDoc.get("title") != null) { token = new StandardAnalyzer().tokenStream("title", new StringReader(hitDoc.get("title"))); fragment = titleHighlighter.getBestFragments(token, hitDoc.get("title"), luceneSettings.getNumFragments(), HIGHLIGHT_SEPARATOR); if (fragment.length() != 0) { resItem.addField(new HighlightField("title", fragment)); } } // Description if (hitDoc.get("description") != null) { token = new StandardAnalyzer().tokenStream("description", new StringReader(hitDoc.get("description"))); fragment = titleHighlighter.getBestFragments(token, hitDoc.get("description"), luceneSettings.getNumFragments(), HIGHLIGHT_SEPARATOR); if (fragment.length() != 0) { resItem.addField(new HighlightField("description", fragment)); } } // All content for (int j = 0; j < fields.length; j++) { // Do not add metaData Field, since this information is stored redundant in lom* fields if (fields[j].equals("metaData")) { continue; } if (fields[j].equals("title") || fields[j].equals("description")) { continue; } Field[] separatedFields = hitDoc.getFields(fields[j]); for (int k = 0; k < separatedFields.length; k++) { allContent.append(separatedFields[k].stringValue()); allContent.append(" "); } } //logger.debug("All content" + allContent.toString()); token = new StandardAnalyzer().tokenStream("content", new StringReader(allContent.toString())); fragment = highlighter.getBestFragments(token, allContent.toString(), luceneSettings.getNumFragments(), HIGHLIGHT_SEPARATOR); //logger.debug("Fragmented: " + fragment); if (fragment.length() != 0) { //logger.debug("Found fragment: " + fragment); resItem.addField(new HighlightField("content", fragment)); } } } /** * @throws ConfigurationException * @throws IOException * @throws SQLException * */ private void init() throws ConfigurationException, IOException, SQLException { // init lucene settings luceneSettings = LuceneSettings.getInstance(); // init highlighter QueryScorer queryScorer = new QueryScorer(query); SimpleHTMLFormatter formatter = new SimpleHTMLFormatter(HIGHLIGHT_BEGIN_TAG, HIGHLIGHT_END_TAG); // Default highlighter highlighter = new Highlighter(formatter, queryScorer); Fragmenter fragmenter = new SimpleFragmenter(luceneSettings.getFragmentSize()); highlighter.setTextFragmenter(fragmenter); highlighter.setMaxDocCharsToAnalyze(Integer.MAX_VALUE); // Title description highlighter -> bigger FRAGMENT SIZE titleHighlighter = new Highlighter(formatter, queryScorer); Fragmenter titleFragmenter = new SimpleFragmenter(FRAGMENT_TITLE_SIZE); titleHighlighter.setTextFragmenter(titleFragmenter); // init fieldinfo fieldInfo = FieldInfo.getInstance(LocalSettings.getClientKey()); // init searcher searcher = SearchHolder.getInstance().getSearcher(); return; } /** * @return */ public String toXML() { return result.toXML(); } }