1 /* XsltFilter.java -- 2 Copyright (C) 2001 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 package gnu.xml.pipeline; 39 40 import java.io.IOException; 41 42 import javax.xml.transform.TransformerFactory; 43 import javax.xml.transform.TransformerConfigurationException; 44 import javax.xml.transform.sax.*; 45 import javax.xml.transform.stream.StreamSource; 46 47 import org.xml.sax.SAXException; 48 import org.xml.sax.ext.LexicalHandler; 49 50 51 /** 52 * Packages an XSLT transform as a pipeline component. 53 * Note that all DTD events (callbacks to DeclHandler and DTDHandler 54 * interfaces) are discarded, although XSLT transforms may be set up to 55 * use the LexicalHandler to write DTDs with only an external subset. 56 * Not every XSLT engine will necessarily be usable with this filter, 57 * but current versions of 58 * <a href="http://saxon.sourceforge.net">SAXON</a> and 59 * <a href="http://xml.apache.org/xalan-j">Xalan</a> should work well. 60 * 61 * @see TransformerFactory 62 * 63 * @author David Brownell 64 */ 65 final public class XsltFilter extends EventFilter 66 { 67 /** 68 * Creates a filter that performs the specified transform. 69 * Uses the JAXP 1.1 interfaces to access the default XSLT 70 * engine configured for in the current execution context, 71 * and parses the stylesheet without custom EntityResolver 72 * or ErrorHandler support. 73 * 74 * @param stylesheet URI for the stylesheet specifying the 75 * XSLT transform 76 * @param next provides the ContentHandler and LexicalHandler 77 * to receive XSLT output. 78 * @exception SAXException if the stylesheet can't be parsed 79 * @exception IOException if there are difficulties 80 * bootstrapping the XSLT engine, such as it not supporting 81 * SAX well enough to use this way. 82 */ XsltFilter(String stylesheet, EventConsumer next)83 public XsltFilter (String stylesheet, EventConsumer next) 84 throws SAXException, IOException 85 { 86 // First, get a transformer with the stylesheet preloaded 87 TransformerFactory tf = null; 88 TransformerHandler th; 89 90 try { 91 SAXTransformerFactory stf; 92 93 tf = TransformerFactory.newInstance (); 94 if (!tf.getFeature (SAXTransformerFactory.FEATURE) // sax inputs 95 || !tf.getFeature (SAXResult.FEATURE) // sax outputs 96 || !tf.getFeature (StreamSource.FEATURE) // stylesheet 97 ) 98 throw new IOException ("XSLT factory (" 99 + tf.getClass ().getName () 100 + ") does not support SAX"); 101 stf = (SAXTransformerFactory) tf; 102 th = stf.newTransformerHandler (new StreamSource (stylesheet)); 103 } catch (TransformerConfigurationException e) { 104 throw new IOException ("XSLT factory (" 105 + (tf == null 106 ? "none available" 107 : tf.getClass ().getName ()) 108 + ") configuration error, " 109 + e.getMessage () 110 ); 111 } 112 113 // Hook its outputs up to the pipeline ... 114 SAXResult out = new SAXResult (); 115 116 out.setHandler (next.getContentHandler ()); 117 try { 118 LexicalHandler lh; 119 lh = (LexicalHandler) next.getProperty (LEXICAL_HANDLER); 120 out.setLexicalHandler (lh); 121 } catch (Exception e) { 122 // ignore 123 } 124 th.setResult (out); 125 126 // ... and make sure its inputs look like ours. 127 setContentHandler (th); 128 setProperty (LEXICAL_HANDLER, th); 129 } 130 } 131