/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Exoffice Technologies. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Exoffice Technologies. Exolab is a registered
* trademark of Exoffice Technologies.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 2001,2003 (C) Exoffice Technologies Inc. All Rights Reserved.
*
* $Id: AttributeExpander.java,v 1.1 2004/11/26 01:50:41 tanderson Exp $
*/
package org.exolab.jms.config;
import java.io.IOException;
import java.io.Reader;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.exolab.castor.util.Configuration;
import org.exolab.castor.xml.EventProducer;
import org.xml.sax.AttributeList;
import org.xml.sax.DocumentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.Parser;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributeListImpl;
/**
* This class expands attributes in XML documents as the document is being
* parsed. It is designed to be used in conjunction with the Castor
* unmarshalling framework.
* <p>
* To be expanded, attribute values must contain text of the form
* <i>${property.name}</i>, where <i>property.name</i> is a property returned
* by <code>System.getProperty()</code>.<br>
* If no property exists, the attribute value remains unchanged.
*
* @version $Revision: 1.1 $ $Date: 2004/11/26 01:50:41 $
* @author <a href="mailto:tima@intalio.com">Tim Anderson</a>
* @see EventProducer
* @see org.exolab.castor.xml.Unmarshaller
*/
public class AttributeExpander implements EventProducer {
private DocumentHandler _handler = null;
private Reader _reader = null;
/**
* The logger
*/
private static final Log _log =
LogFactory.getLog(AttributeExpander.class);
/**
* Construct a new instance
*
* @param reader the XML file reader
*/
public AttributeExpander(Reader reader) {
_reader = reader;
}
/**
* Sets the DocumentHandler to send SAX events to
*/
public void setDocumentHandler(DocumentHandler handler) {
_handler = handler;
}
/**
* Signals to start producing events.
*/
public void start() throws SAXException {
Parser parser = Configuration.getDefaultParser();
if (parser == null) {
throw new SAXException("Unable to create parser");
}
DocumentHandler handler = new AttributeInterceptor();
parser.setDocumentHandler(handler);
try {
parser.parse(new InputSource(_reader));
} catch (IOException exception) {
throw new SAXException(exception.getMessage(), exception);
}
}
/**
* Helper class to intercept {@link #startElement} calls, expanding
* any attributes.
*/
private class AttributeInterceptor implements DocumentHandler {
public void setDocumentLocator(Locator locator) {
_handler.setDocumentLocator(locator);
}
public void startDocument() throws SAXException {
_handler.startDocument();
}
public void endDocument() throws SAXException {
_handler.endDocument();
}
public void startElement(String name, AttributeList list)
throws SAXException {
AttributeListImpl replaced = new AttributeListImpl();
for (int i = 0; i < list.getLength(); i++) {
String value = expand(list.getName(i), list.getValue(i));
replaced.addAttribute(list.getName(i), list.getType(i), value);
}
_handler.startElement(name, replaced);
}
public void endElement(String name) throws SAXException {
_handler.endElement(name);
}
public void characters(char[] ch, int start, int length)
throws SAXException {
_handler.characters(ch, start, length);
}
public void ignorableWhitespace(char[] ch, int start, int length)
throws SAXException {
_handler.ignorableWhitespace(ch, start, length);
}
public void processingInstruction(String target, String data)
throws SAXException {
_handler.processingInstruction(target, data);
}
private String expand(String attribute, String value) {
StringBuffer buffer = new StringBuffer();
int prev = 0;
int pos;
while ((pos = value.indexOf("${", prev)) >= 0) {
if (pos > 0) {
buffer.append(value.substring(prev, pos));
}
int index = value.indexOf('}', pos);
if (index < 0) {
// invalid format
_log.warn("Cannot expand " + attribute
+ " - invalid format: " + value);
buffer.append("${");
prev = pos + 2;
} else {
String name = value.substring(pos + 2, index);
String property = System.getProperty(name);
if (property != null) {
buffer.append(property);
} else {
// attribute cannot be expanded as the property is
// not defined
_log.warn("Cannot expand " + attribute
+ " as property " + name
+ " is not defined");
buffer.append("${");
buffer.append(name);
buffer.append("}");
}
prev = index + 1;
}
}
if (prev < value.length()) {
buffer.append(value.substring(prev));
}
String result = buffer.toString();
return result;
}
} //-- AttributeInterceptor
} //-- AttributeExpander