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/*
Calimero 2 - A library for KNX network access
Copyright (c) 2006, 2011 B. Malinowsky
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Linking this library statically or dynamically with other modules is
making a combined work based on this library. Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.
As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under terms
of your choice, provided that you also meet, for each linked independent
module, the terms and conditions of the license of that module. An
independent module is a module which is not derived from or based on
this library. If you modify this library, you may extend this exception
to your version of the library, but you are not obligated to do so. If
you do not wish to do so, delete this exception statement from your
version.
*/
package tuwien.auto.calimero.xml;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
/**
* Creates XML reader and XML writer for working with XML resources.
*
* A {@link XMLWriter} and {@link XMLReader} is created using its default constructor,
* i.e., every implementation is required to supply such a constructor.
* By default, the factory creates instances of types located in the def
* sub package.
* The factory uses an {@link EntityResolver} to resolve XML resources.
*
* Note that for now only one default XML reader/writer is available in this factory, and
* therefore can't be changed.
*
* @author B. Malinowsky
*/
public final class XMLFactory
{
// if we have more than one reader/writer implementation or wrappers for other
// XML processing tools, appropriate selection methods will be provided
private static final String DEFAULT_READER =
"tuwien.auto.calimero.xml.def.DefaultXMLReader";
private static final String DEFAULT_WRITER =
"tuwien.auto.calimero.xml.def.DefaultXMLWriter";
private static final String DEFAULT_RESOLVER =
"tuwien.auto.calimero.xml.def.DefaultEntityResolver";
private XMLFactory()
{}
/**
* Gets the XML factory.
*
*
* @return XMLFactory object
*/
public static XMLFactory getInstance()
{
return FactoryHolder.f;
}
/**
* Creates a {@link XMLReader} to read the XML resource located by the specified
* identifier.
*
* On closing the created XML reader, the {@link Reader} set as input for the XML
* reader will get closed as well.
*
* @param systemID location identifier of the XML resource
* @return XML reader
* @throws KNXMLException if creation of the reader failed or XML resource can't be
* resolved
*/
public XMLReader createXMLReader(final String systemID) throws KNXMLException
{
final XMLReader r = (XMLReader) create(DEFAULT_READER);
final EntityResolver res = (EntityResolver) create(DEFAULT_RESOLVER);
final InputStream is = res.resolveInput(systemID);
try {
r.setInput(res.getInputReader(is), true);
}
catch (final KNXMLException e) {
try {
is.close();
}
catch (final IOException ignore) {}
throw e;
}
return r;
}
/**
* Creates a {@link XMLWriter} to write into the XML resource located by the specified
* identifier.
*
*
* @param systemID location identifier of the XML resource
* @return XML writer
* @throws KNXMLException if creation of the writer failed or XML resource can't be
* resolved
*/
public XMLWriter createXMLWriter(final String systemID) throws KNXMLException
{
final XMLWriter w = (XMLWriter) create(DEFAULT_WRITER);
final EntityResolver res = (EntityResolver) create(DEFAULT_RESOLVER);
final OutputStream os = res.resolveOutput(systemID);
try {
w.setOutput(new OutputStreamWriter(os, "UTF-8"), true);
return w;
}
catch (final UnsupportedEncodingException e) {
try {
os.close();
}
catch (final IOException ignore) {}
throw new KNXMLException("encoding UTF-8 unknown");
}
}
private Object create(final String className) throws KNXMLException
{
try {
return Class.forName(className).newInstance();
}
catch (final SecurityException e) {
throw new KNXMLException("loading XML handler not allowed, " + e.getMessage());
}
catch (final Exception e) {
// InstantiationException, IllegalAccessException, ClassNotFoundException
throw new KNXMLException("failed to create XML handler, " + e.getMessage());
}
}
private static final class FactoryHolder
{
static final XMLFactory f = new XMLFactory();
private FactoryHolder()
{}
}
}