org.apache.commons.configuration2.HierarchicalConfigurationXMLReader Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.configuration2;
import org.apache.commons.configuration2.tree.ConfigurationNodeVisitorAdapter;
import org.apache.commons.configuration2.tree.NodeHandler;
import org.apache.commons.configuration2.tree.NodeTreeWalker;
import org.xml.sax.Attributes;
import org.xml.sax.helpers.AttributesImpl;
/**
*
* A specialized SAX2 XML parser that "parses" hierarchical configuration
* objects.
*
*
* This class mimics to be a SAX conform XML parser. Instead of parsing XML
* documents it processes a {@code Configuration} object and generates SAX
* events for the single properties defined there. This enables the whole world
* of XML processing for configuration objects.
*
*
* The {@code HierarchicalConfiguration} object to be parsed can be specified
* using a constructor or the {@code setConfiguration()} method. This object
* will be processed by the {@code parse()} methods. Note that these methods
* ignore their argument.
*
*
* @param the type of the nodes supported by this reader
*/
public class HierarchicalConfigurationXMLReader extends
ConfigurationXMLReader
{
/** Stores the configuration object to be parsed. */
private HierarchicalConfiguration configuration;
/**
* Creates a new instance of {@code HierarchicalConfigurationXMLReader}.
*/
public HierarchicalConfigurationXMLReader()
{
super();
}
/**
* Creates a new instance of {@code HierarchicalConfigurationXMLReader} and
* sets the configuration to be parsed.
*
* @param config the configuration object
*/
public HierarchicalConfigurationXMLReader(
final HierarchicalConfiguration config)
{
this();
setConfiguration(config);
}
/**
* Returns the configuration object to be parsed.
*
* @return the configuration object to be parsed
*/
public HierarchicalConfiguration getConfiguration()
{
return configuration;
}
/**
* Sets the configuration object to be parsed.
*
* @param config the configuration object to be parsed
*/
public void setConfiguration(final HierarchicalConfiguration config)
{
configuration = config;
}
/**
* Returns the configuration object to be processed.
*
* @return the actual configuration object
*/
@Override
public Configuration getParsedConfiguration()
{
return getConfiguration();
}
/**
* Processes the actual configuration object to generate SAX parsing events.
*/
@Override
protected void processKeys()
{
final NodeHandler nodeHandler =
getConfiguration().getNodeModel().getNodeHandler();
NodeTreeWalker.INSTANCE.walkDFS(nodeHandler.getRootNode(),
new SAXVisitor(), nodeHandler);
}
/**
* A specialized visitor class for generating SAX events for a hierarchical
* node structure.
*/
private class SAXVisitor extends ConfigurationNodeVisitorAdapter
{
/** Constant for the attribute type. */
private static final String ATTR_TYPE = "CDATA";
/**
* Visits the specified node after its children have been processed.
*
* @param node the actual node
* @param handler the node handler
*/
@Override
public void visitAfterChildren(final T node, final NodeHandler handler)
{
fireElementEnd(nodeName(node, handler));
}
/**
* Visits the specified node.
*
* @param node the actual node
* @param handler the node handler
*/
@Override
public void visitBeforeChildren(final T node, final NodeHandler handler)
{
fireElementStart(nodeName(node, handler),
fetchAttributes(node, handler));
final Object value = handler.getValue(node);
if (value != null)
{
fireCharacters(value.toString());
}
}
/**
* Checks if iteration should be terminated. This implementation stops
* iteration after an exception has occurred.
*
* @return a flag if iteration should be stopped
*/
@Override
public boolean terminate()
{
return getException() != null;
}
/**
* Returns an object with all attributes for the specified node.
*
* @param node the current node
* @param handler the node handler
* @return an object with all attributes of this node
*/
protected Attributes fetchAttributes(final T node, final NodeHandler handler)
{
final AttributesImpl attrs = new AttributesImpl();
for (final String attr : handler.getAttributes(node))
{
final Object value = handler.getAttributeValue(node, attr);
if (value != null)
{
attrs.addAttribute(NS_URI, attr, attr, ATTR_TYPE,
value.toString());
}
}
return attrs;
}
/**
* Helper method for determining the name of a node. If a node has no
* name (which is true for the root node), the specified default name
* will be used.
*
* @param node the node to be checked
* @param handler the node handler
* @return the name for this node
*/
private String nodeName(final T node, final NodeHandler handler)
{
final String nodeName = handler.nodeName(node);
return nodeName == null ? getRootName() : nodeName;
}
}
}