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jeremybenn |
/* XsltFilter.java --
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Copyright (C) 2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.xml.pipeline;
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import java.io.IOException;
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import javax.xml.transform.TransformerFactory;
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import javax.xml.transform.TransformerConfigurationException;
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import javax.xml.transform.sax.*;
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import javax.xml.transform.stream.StreamSource;
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import org.xml.sax.SAXException;
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import org.xml.sax.ext.LexicalHandler;
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/**
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* Packages an XSLT transform as a pipeline component.
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* Note that all DTD events (callbacks to DeclHandler and DTDHandler
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* interfaces) are discarded, although XSLT transforms may be set up to
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* use the LexicalHandler to write DTDs with only an external subset.
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* Not every XSLT engine will necessarily be usable with this filter,
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* but current versions of
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* <a href="http://saxon.sourceforge.net">SAXON</a> and
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* <a href="http://xml.apache.org/xalan-j">Xalan</a> should work well.
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*
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* @see TransformerFactory
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*
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* @author David Brownell
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*/
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final public class XsltFilter extends EventFilter
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{
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/**
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* Creates a filter that performs the specified transform.
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* Uses the JAXP 1.1 interfaces to access the default XSLT
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* engine configured for in the current execution context,
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* and parses the stylesheet without custom EntityResolver
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* or ErrorHandler support.
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*
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* @param stylesheet URI for the stylesheet specifying the
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* XSLT transform
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* @param next provides the ContentHandler and LexicalHandler
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* to receive XSLT output.
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* @exception SAXException if the stylesheet can't be parsed
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* @exception IOException if there are difficulties
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* bootstrapping the XSLT engine, such as it not supporting
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* SAX well enough to use this way.
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*/
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public XsltFilter (String stylesheet, EventConsumer next)
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throws SAXException, IOException
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{
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// First, get a transformer with the stylesheet preloaded
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TransformerFactory tf = null;
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TransformerHandler th;
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try {
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SAXTransformerFactory stf;
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tf = TransformerFactory.newInstance ();
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if (!tf.getFeature (SAXTransformerFactory.FEATURE) // sax inputs
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|| !tf.getFeature (SAXResult.FEATURE) // sax outputs
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|| !tf.getFeature (StreamSource.FEATURE) // stylesheet
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)
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throw new IOException ("XSLT factory ("
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+ tf.getClass ().getName ()
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+ ") does not support SAX");
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stf = (SAXTransformerFactory) tf;
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th = stf.newTransformerHandler (new StreamSource (stylesheet));
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} catch (TransformerConfigurationException e) {
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throw new IOException ("XSLT factory ("
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+ (tf == null
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? "none available"
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: tf.getClass ().getName ())
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+ ") configuration error, "
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+ e.getMessage ()
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);
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}
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// Hook its outputs up to the pipeline ...
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SAXResult out = new SAXResult ();
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out.setHandler (next.getContentHandler ());
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try {
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LexicalHandler lh;
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lh = (LexicalHandler) next.getProperty (LEXICAL_HANDLER);
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out.setLexicalHandler (lh);
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} catch (Exception e) {
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// ignore
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}
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th.setResult (out);
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// ... and make sure its inputs look like ours.
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setContentHandler (th);
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setProperty (LEXICAL_HANDLER, th);
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}
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}
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