    001    //$HeadURL: https://svn.wald.intevation.org/svn/deegree/base/branches/2.4_testing/src/org/deegree/portal/context/ContextTransformer.java $
    002    /*----------------------------------------------------------------------------
    003     This file is part of deegree, http://deegree.org/
    004     Copyright (C) 2001-2009 by:
    005       Department of Geography, University of Bonn
    006     and
    007       lat/lon GmbH
    008
    009     This library is free software; you can redistribute it and/or modify it under
    010     the terms of the GNU Lesser General Public License as published by the Free
    011     Software Foundation; either version 2.1 of the License, or (at your option)
    012     any later version.
    013     This library is distributed in the hope that it will be useful, but WITHOUT
    014     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    015     FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
    016     details.
    017     You should have received a copy of the GNU Lesser General Public License
    018     along with this library; if not, write to the Free Software Foundation, Inc.,
    019     59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    020
    021     Contact information:
    022
    023     lat/lon GmbH
    024     Aennchenstr. 19, 53177 Bonn
    025     Germany
    026     http://lat-lon.de/
    027
    028     Department of Geography, University of Bonn
    029     Prof. Dr. Klaus Greve
    030     Postfach 1147, 53001 Bonn
    031     Germany
    032     http://www.geographie.uni-bonn.de/deegree/
    033
    034     e-mail: info@deegree.org
    035    ----------------------------------------------------------------------------*/
    036
    037    package org.deegree.portal.context;
    038
    039    import java.io.IOException;
    040    import java.io.InputStream;
    041    import java.io.StringWriter;
    042
    043    import javax.xml.transform.Transformer;
    044    import javax.xml.transform.TransformerConfigurationException;
    045    import javax.xml.transform.TransformerException;
    046    import javax.xml.transform.TransformerFactory;
    047    import javax.xml.transform.TransformerFactoryConfigurationError;
    048    import javax.xml.transform.stream.StreamResult;
    049    import javax.xml.transform.stream.StreamSource;
    050
    051    import org.deegree.framework.log.ILogger;
    052    import org.deegree.framework.log.LoggerFactory;
    053
    054    /**
    055     * Singleton class capsulating a <code>javax.xml.transform.Transformer</code>. This class is used
    056     * to transform a map context xml document in a html document used the transformation (xslt)
    057     * provided.
    058     *
    059     * @author <a href="mailto:taddei@lat-lon.de">Ugo Taddei</a>
    060     *
    061     */
    062    public class ContextTransformer {
    063
    064        private static final ILogger LOG = LoggerFactory.getLogger( ContextTransformer.class );
    065
    066        /**
    067         * The <code>Transformer</code> object used in the transformation of a map context xml to
    068         * html.
    069         */
    070        protected static Transformer transformer = null;
    071
    072        private static final ContextTransformer INSTANCE = new ContextTransformer();
    073
    074
    075        private ContextTransformer() {
    076            // Forbid instantiation
    077        }
    078
    079        private static void initTransformer( InputStream is ) {
    080
    081            try {
    082                TransformerFactory tFactory = TransformerFactory.newInstance();
    083                transformer = tFactory.newTransformer( new StreamSource( is ) );
    084            } catch ( TransformerConfigurationException e ) {
    085                e.printStackTrace();
    086            } catch ( TransformerFactoryConfigurationError e ) {
    087                e.printStackTrace();
    088            }
    089        }
    090
    091        /**
    092         * @return the singleton.
    093         */
    094        public static ContextTransformer getInstance() {
    095            return INSTANCE;
    096        }
    097
    098        /**
    099         * Transforms the context pointed to by <code>context</code> into html using
    100         * <code>xsltURL</code> (though this is currently fixed; there's really no need to define
    101         * one's wn xsl).
    102         *
    103         * @param xsl
    104         *            the <code>InputStream</code> containing the xls
    105         * @param contxt
    106         *            the <code>InputStream</code> containing the context to be transformed
    107         * @return the converted string.
    108         * @throws TransformerException
    109         */
    110        public String transformContext( InputStream xsl, InputStream contxt )
    111                                throws TransformerException {
    112
    113            StringWriter sw = new StringWriter();
    114
    115            if ( transformer == null ) { // needs to instantiate transformer
    116                initTransformer( xsl );
    117            }
    118            if ( transformer == null ) {
    119                LOG.logInfo( "transformer is still null" );
    120            }
    121            StreamResult sr = new StreamResult( sw );
    122            StreamSource sSrc = new StreamSource( contxt );
    123            transformer.transform( sSrc, sr );
    124
    125            try {
    126                sw.close();
    127            } catch ( IOException e ) {
    128                LOG.logError( "Unable to close string writer.", e );
    129            }
    130
    131            return sw.toString();
    132        }
    133
    134        @Override
    135        public String toString() {
    136            return transformer.toString();
    137        }
    138    }