org.opencms.search.documents.CmsTermHighlighterHtml Maven / Gradle / Ivy
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/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the m_terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* For further information about Alkacon Software GmbH & Co. KG, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.opencms.search.documents;
import org.opencms.i18n.CmsEncoder;
import org.opencms.main.OpenCms;
import org.opencms.search.CmsSearchIndex;
import org.opencms.search.CmsSearchParameters;
import org.opencms.search.fields.CmsLuceneFieldConfiguration;
import java.io.IOException;
import java.io.StringReader;
import java.util.Iterator;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.document.Document;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
import org.apache.lucene.search.highlight.QueryTermScorer;
/**
* Default highlighter implementation used for generation of search excerpts.
*
* @since 6.0.0
*/
public class CmsTermHighlighterHtml implements I_CmsTermHighlighter {
/** Separator for the search excerpt fragments. */
private static final String EXCERPT_FRAGMENT_SEPARATOR = " ... ";
/** Fragments required in excerpt. */
private static final int EXCERPT_REQUIRED_FRAGMENTS = 5;
/**
* @see org.opencms.search.documents.I_CmsTermHighlighter#getExcerpt(org.apache.lucene.document.Document, org.opencms.search.CmsSearchIndex, org.opencms.search.CmsSearchParameters, org.apache.lucene.search.Query, org.apache.lucene.analysis.Analyzer)
*/
public String getExcerpt(
Document doc,
CmsSearchIndex index,
CmsSearchParameters params,
Query query,
Analyzer analyzer) throws IOException, InvalidTokenOffsetsException {
if ((doc == null) || (index == null) || (params == null) || (analyzer == null) || (query == null)) {
return null;
}
if (!(index.getFieldConfiguration() instanceof CmsLuceneFieldConfiguration)) {
// also return null if the field configuration is not a lucene field configuration
return null;
}
Highlighter highlighter = null;
CmsLuceneFieldConfiguration conf = (CmsLuceneFieldConfiguration)index.getFieldConfiguration();
Iterator excerptFieldNames = conf.getExcerptFieldNames().iterator();
StringBuffer excerptBuffer = new StringBuffer();
while (excerptFieldNames.hasNext()) {
String fieldName = excerptFieldNames.next();
boolean createExcerpt = !params.isExcerptOnlySearchedFields() || params.getFields().contains(fieldName);
if (createExcerpt && (doc.getField(fieldName) != null)) {
// only generate field excerpt if the field is available in the document
String text = doc.getField(fieldName).stringValue();
// make sure all XML in the text is escaped, otherwise excerpt HTML output may be garbled
text = CmsEncoder.escapeXml(text);
TokenStream stream = analyzer.tokenStream(fieldName, new StringReader(text));
if (params.isExcerptOnlySearchedFields()) {
// highlight the search query only in the matching fields
highlighter = new Highlighter(new QueryTermScorer(query, fieldName));
} else {
// highlight search query in all fields
if (highlighter == null) {
highlighter = new Highlighter(new QueryTermScorer(query));
}
}
String fragment = highlighter.getBestFragments(
stream,
text,
EXCERPT_REQUIRED_FRAGMENTS,
EXCERPT_FRAGMENT_SEPARATOR);
// kill all unwanted chars in the excerpt
fragment = fragment.replace('\t', ' ');
fragment = fragment.replace('\n', ' ');
fragment = fragment.replace('\r', ' ');
fragment = fragment.replace('\f', ' ');
if (excerptBuffer.length() > 0) {
// this is not the first fragment
excerptBuffer.append(EXCERPT_FRAGMENT_SEPARATOR);
}
excerptBuffer.append(fragment);
}
}
String result = null;
if (excerptBuffer.length() > 0) {
result = excerptBuffer.toString();
}
int maxLength = OpenCms.getSearchManager().getMaxExcerptLength();
if ((result != null) && (result.length() > maxLength)) {
result = result.substring(0, maxLength);
}
return result;
}
}