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Provides common utility functions
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/*
* Copyright (c) CQSE 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 org.conqat.lib.commons.xml;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
* Base class for SAX parser handlers. This class has a default implementation of
* {@link #resolveEntity(String, String)} that works around a bug in the Java SAX parser
* implementation:
*
* If {@link #resolveEntity(String, String)} returns null
for a given DTD (the default
* behavior of {@link DefaultHandler}), the Java SAX parser will try to download that DTD. This will
* fail on machines that have no Internet connection or require a proxy to access the Internet or
* for DTDs where the URI is not a valid URL. This class' default implementation instead returns an
* empty {@link InputSource}, which effectively causes the parser to skip DTD validation.
*
* Please note that downloading the DTD from the Internet is against the DTD specification (as the
* DTD URI is not required to be a valid URL) and is highly error-prone, resulting in a hard to
* interpret error message. It is thus recommended you use this base class and never return
* null
from {@link #resolveEntity(String, String)}.
*/
public class OfflineSaxHandlerBase extends DefaultHandler {
/**
* {@inheritDoc}
*
* Default implementation that can be overwritten by subclasses. This implementation returns an
* empty document for any entity that should be resolved. This effectively causes the parser to skip
* DTD validation.
*
* @throws IOException
* may be thrown by subclasses.
* @throws SAXException
* may be thrown by subclasses.
*/
@Override
public InputSource resolveEntity(String publicId, String systemId) throws IOException, SAXException {
return new InputSource(new ByteArrayInputStream(new byte[0]));
}
}