/*
* Copyright 2006-2009 Odysseus Software GmbH
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package de.odysseus.el.samples.xml.sax;
import java.io.IOException;
import java.io.StringReader;
import javax.el.ELContext;
import javax.el.ELException;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.AttributesImpl;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.helpers.XMLReaderFactory;
import de.odysseus.el.util.SimpleContext;
/**
* SAX filter to provide attribute values as evaluated expressions.
* See the <code>main(...)</code> method for a usage example.
*
* @author Christoph Beck
*/
public class AttributesFilter extends AbstractFilter {
public AttributesFilter(XMLReader parent, ELContext context) {
super(parent, context);
}
@Override
public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
AttributesImpl atts2 = new AttributesImpl(atts);
for (int i = 0; i < atts2.getLength(); i++) {
try {
atts2.setValue(i, eval(atts2.getValue(i)));
} catch (ELException e) {
throw new SAXException("Error evaluating " + localName + "@" + atts.getLocalName(i), e);
}
}
super.startElement(uri, localName, qName, atts2);
}
/**
* Usage example.
*/
public static void main(String[] args) throws SAXException, IOException {
// create our expression context
ELContext context = new SimpleContext();
// set value for top-level property "home"
context.getELResolver().setValue(context, null, "home", "/foo/bar");
// create our filtered reader
XMLReader reader = new AttributesFilter(XMLReaderFactory.createXMLReader(), context);
// simple test content handler to print elements and attributes to stdout
reader.setContentHandler(new DefaultHandler() {
@Override
public void startElement(String uri, String localName, String qName, Attributes attributes) {
System.out.println("start " + localName);
for (int i = 0; i < attributes.getLength(); i++) {
System.out.println(" @" + attributes.getLocalName(i) + " = " + attributes.getValue(i));
}
}
@Override
public void endElement(String uri, String localName, String qName) {
System.out.println("end " + localName);
}
@Override
public void characters(char[] ch, int start, int length) throws SAXException {
System.out.println("text: " + new String(ch, start, length));
}
});
// parse our test input and watch the evaluated attributes
String xml ="<test>foo<math>1+2=${1+2}</math><config file='${home}/config.xml'/>bar</test>";
reader.parse(new InputSource(new StringReader(xml)));
}
}