src/java/org/apache/commons/configuration/XMLConfiguration.java - commons-configuration - Git at Google

 /*
  * Copyright 2004 The Apache Software Foundation.
  *
  * 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.apache.commons.configuration;

 import java.io.File;
 import java.io.Reader;
 import java.io.StringWriter;
 import java.io.Writer;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.transform.Result;
 import javax.xml.transform.Source;
 import javax.xml.transform.Transformer;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
 import javax.xml.transform.stream.StreamResult;

 import org.apache.commons.lang.StringUtils;
 import org.w3c.dom.Attr;
 import org.w3c.dom.CDATASection;
 import org.w3c.dom.CharacterData;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NamedNodeMap;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 import org.w3c.dom.Text;
 import org.xml.sax.InputSource;

 /**
  * Reads a XML configuration file.
  *
  * To retrieve the value of an attribute of an element, use
  * <code>X.Y.Z[@attribute]</code>. The '@' symbol was chosen for consistency
  * with XPath.
  *
  * Setting property values will <b>NOT </b> automatically persist changes to
  * disk, unless <code>autoSave=true</code>.
  *
  * @since commons-configuration 1.0
  *
  * @author Jörg Schaible
  * @author <a href="mailto:kelvint@apache.org">Kelvin Tan </a>
  * @author <a href="mailto:dlr@apache.org">Daniel Rall </a>
  * @author Emmanuel Bourg
  * @version $Revision: 1.17 $, $Date: 2004/10/04 19:35:45 $
  */
 public class XMLConfiguration extends AbstractFileConfiguration
 {
     // For conformance with xpath
     private static final String ATTRIBUTE_START = "[@";

     private static final String ATTRIBUTE_END = "]";

     /**
      * For consistency with properties files. Access nodes via an "A.B.C"
      * notation.
      */
     private static final String NODE_DELIMITER = ".";

     /**
      * The XML document from our data source.
      */
     private Document document;

     /**
      * If true, modifications are immediately persisted.
      */
     private boolean autoSave = false;

     /**
      * Creates an empty XML configuration.
      */
     public XMLConfiguration()
     {
         // build an empty document.
         DocumentBuilder builder = null;
         try
         {
             builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
         }
         catch (ParserConfigurationException e)
         {
             throw new ConfigurationRuntimeException(e.getMessage(), e);
         }

         document = builder.newDocument();
         document.appendChild(document.createElement("configuration"));
     }

     /**
      * Creates and loads the XML configuration from the specified resource.
      *
      * @param resource The name of the resource to load.
      *
      * @throws ConfigurationException Error while loading the XML file
      */
     public XMLConfiguration(String resource) throws ConfigurationException
     {
         this.fileName = resource;
         url = ConfigurationUtils.locate(resource);
         load();
     }

     /**
      * Creates and loads the XML configuration from the specified file.
      *
      * @param file The XML file to load.
      * @throws ConfigurationException Error while loading the XML file
      */
     public XMLConfiguration(File file) throws ConfigurationException
     {
         setFile(file);
         load();
     }

     /**
      * Creates and loads the XML configuration from the specified URL.
      *
      * @param url The location of the XML file to load.
      * @throws ConfigurationException Error while loading the XML file
      */
     public XMLConfiguration(URL url) throws ConfigurationException
     {
         setURL(url);
         load();
     }

     /**
      * {@inheritDoc}
      */
     public void load(Reader in) throws ConfigurationException
     {
         try
         {
             DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
             document = builder.parse(new InputSource(in));
         }
         catch (Exception e)
         {
             throw new ConfigurationException(e.getMessage(), e);
         }

         initProperties(document.getDocumentElement(), new StringBuffer());
     }

     /**
      * Loads and initializes from the XML file.
      *
      * @param element The element to start processing from. Callers should supply the root element of the document.
      * @param hierarchy
      */
     private void initProperties(Element element, StringBuffer hierarchy)
     {
         StringBuffer buffer = new StringBuffer();
         NodeList list = element.getChildNodes();
         for (int i = 0; i < list.getLength(); i++)
         {
             Node node = list.item(i);
             if (node instanceof Element)
             {
                 Element child = (Element) node;

                 StringBuffer subhierarchy = new StringBuffer(hierarchy.toString());
                 subhierarchy.append(child.getTagName());
                 processAttributes(subhierarchy.toString(), child);
                 initProperties(child, subhierarchy.append(NODE_DELIMITER));
             }
             else if (node instanceof CDATASection || node instanceof Text)
             {
                 CharacterData data = (CharacterData) node;
                 buffer.append(data.getData());
             }
         }

         String text = buffer.toString().trim();
         if (text.length() > 0 && hierarchy.length() > 0)
         {
             super.addProperty(hierarchy.substring(0, hierarchy.length() - 1), text);
         }
     }

     /**
      * Helper method for constructing properties for the attributes of the given
      * XML element.
      *
      * @param hierarchy the actual hierarchy
      * @param element   the actual XML element
      */
     private void processAttributes(String hierarchy, Element element)
     {
         // Add attributes as x.y{ATTRIBUTE_START}att{ATTRIBUTE_END}
         NamedNodeMap attributes = element.getAttributes();
         for (int i = 0; i < attributes.getLength(); ++i)
         {
             Attr attr = (Attr) attributes.item(i);
             String attrName = hierarchy + ATTRIBUTE_START + attr.getName() + ATTRIBUTE_END;
             super.addProperty(attrName, attr.getValue());
         }
     }

     /**
      * Calls super method, and also ensures the underlying {@linkDocument} is
      * modified so changes are persisted when saved.
      *
      * @param name
      * @param value
      */
     public void addProperty(String name, Object value)
     {
         super.addProperty(name, value);
         addXmlProperty(name, value);
         possiblySave();
     }

     Object getXmlProperty(String name)
     {
         // parse the key
         String[] nodes = parseElementNames(name);
         String attName = parseAttributeName(name);

         // get all the matching elements
         List children = findElementsForPropertyNodes(nodes);

         List properties = new ArrayList();
         if (attName == null)
         {
             // return text contents of elements
             Iterator cIter = children.iterator();
             while (cIter.hasNext())
             {
                 Element child = (Element) cIter.next();
                 // add non-empty strings
                 String text = getChildText(child);
                 if (StringUtils.isNotEmpty(text))
                 {
                     properties.add(text);
                 }
             }
         }
         else
         {
             // return text contents of attributes
             Iterator cIter = children.iterator();
             while (cIter.hasNext())
             {
                 Element child = (Element) cIter.next();
                 if (child.hasAttribute(attName))
                 {
                     properties.add(child.getAttribute(attName));
                 }
             }
         }

         switch (properties.size())
         {
             case 0:
                 return null;
             case 1:
                 return properties.get(0);
             default:
                 return properties;
         }
     }

     /**
      * TODO Add comment.
      *
      * @param nodes
      * @return
      */
     private List findElementsForPropertyNodes(String[] nodes)
     {
         List children = new ArrayList();
         List elements = new ArrayList();

         children.add(document.getDocumentElement());
         for (int i = 0; i < nodes.length; i++)
         {
             elements.clear();
             elements.addAll(children);
             children.clear();

             String eName = nodes[i];
             Iterator eIter = elements.iterator();
             while (eIter.hasNext())
             {
                 Element element = (Element) eIter.next();
                 NodeList list = element.getChildNodes();
                 for (int j = 0; j < list.getLength(); j++)
                 {
                     Node node = list.item(j);
                     if (node instanceof Element)
                     {
                         Element child = (Element) node;
                         if (eName.equals(child.getTagName()))
                         {
                             children.add(child);
                         }
                     }
                 }
             }
         }

         return children;
     }

     private static String getChildText(Node node)
     {
         // is there anything to do?
         if (node == null)
         {
             return null;
         }

         // concatenate children text
         StringBuffer str = new StringBuffer();
         Node child = node.getFirstChild();
         while (child != null)
         {
             short type = child.getNodeType();
             if (type == Node.TEXT_NODE)
             {
                 str.append(child.getNodeValue());
             }
             else if (type == Node.CDATA_SECTION_NODE)
             {
                 str.append(child.getNodeValue());
             }
             child = child.getNextSibling();
         }

         // return text value
         return StringUtils.trimToNull(str.toString());

     }

     private Element getChildElementWithName(String eName, Element element)
     {
         Element child = null;

         NodeList list = element.getChildNodes();
         for (int j = 0; j < list.getLength(); j++)
         {
             Node node = list.item(j);
             if (node instanceof Element)
             {
                 child = (Element) node;
                 if (eName.equals(child.getTagName()))
                 {
                     break;
                 }
                 child = null;
             }
         }
         return child;
     }

     /**
      * Adds the property value in our document tree.
      *
      * @param name  The name of the element to set a value for.
      * @param value The value to set.
      */
     private void addXmlProperty(String name, Object value)
     {
         // parse the key
         String[] nodes = parseElementNames(name);
         String attName = parseAttributeName(name);

         Element element = document.getDocumentElement();
         Element parent = element;

         for (int i = 0; i < nodes.length; i++)
         {
             if (element == null)
             {
                 break;
             }
             parent = element;
             String eName = nodes[i];
             Element child = getChildElementWithName(eName, element);

             element = child;
         }

         Element child = document.createElement(nodes[nodes.length - 1]);
         parent.appendChild(child);
         if (attName == null)
         {
             CharacterData data = document.createTextNode(String.valueOf(value));
             child.appendChild(data);
         }
         else
         {
             child.setAttribute(attName, String.valueOf(value));
         }
     }

     /**
      * Calls super method, and also ensures the underlying {@link Document}is
      * modified so changes are persisted when saved.
      *
      * @param name The name of the property to clear.
      */
     public void clearProperty(String name)
     {
         super.clearProperty(name);
         clearXmlProperty(name);
         possiblySave();
     }

     private void clearXmlProperty(String name)
     {
         // parse the key
         String[] nodes = parseElementNames(name);
         String attName = parseAttributeName(name);

         // get all the matching elements
         List children = findElementsForPropertyNodes(nodes);

         if (attName == null)
         {
             // remove children with no subelements
             Iterator cIter = children.iterator();
             while (cIter.hasNext())
             {
                 Element child = (Element) cIter.next();

                 // determine if child has subelments
                 boolean hasSubelements = false;
                 Node subchild = child.getFirstChild();
                 while (subchild != null)
                 {
                     if (subchild.getNodeType() == Node.ELEMENT_NODE)
                     {
                         hasSubelements = true;
                         break;
                     }
                     subchild = subchild.getNextSibling();
                 }

                 if (!hasSubelements)
                 {
                     // safe to remove
                     if (!child.hasAttributes())
                     {
                         // remove entire node
                         Node parent = child.getParentNode();
                         parent.removeChild(child);
                     }
                     else
                     {
                         // only remove node contents
                         subchild = child.getLastChild();
                         while (subchild != null)
                         {
                             child.removeChild(subchild);
                             subchild = child.getLastChild();
                         }
                     }
                 }
             }
         }
         else
         {
             // remove attributes from children
             Iterator cIter = children.iterator();
             while (cIter.hasNext())
             {
                 Element child = (Element) cIter.next();
                 child.removeAttribute(attName);
             }
         }
     }

     /**
      * Save the configuration if the automatic persistence is enabled and a file
      * is specified.
      */
     private void possiblySave()
     {
         if (autoSave && fileName != null)
         {
             try
             {
                 save();
             }
             catch (ConfigurationException ce)
             {
                 throw new ConfigurationRuntimeException("Failed to auto-save", ce);
             }
         }
     }

     /**
      * If true, changes are automatically persisted.
      *
      * @param autoSave
      */
     public void setAutoSave(boolean autoSave)
     {
         this.autoSave = autoSave;
     }

     /**
      * {@inheritDoc}
      */
     public void save(Writer writer) throws ConfigurationException
     {
         try
         {
             Transformer transformer = TransformerFactory.newInstance().newTransformer();
             Source source = new DOMSource(document);
             Result result = new StreamResult(writer);

             transformer.setOutputProperty("indent", "yes");
             transformer.transform(source, result);
         }
         catch (TransformerException e)
         {
             throw new ConfigurationException(e.getMessage(), e);
         }
     }

     public String toString()
     {
         StringWriter writer = new StringWriter();
         try
         {
             save(writer);
         }
         catch (ConfigurationException e)
         {
             e.printStackTrace();
         }
         return writer.toString();
     }

     /**
      * Parse a property key and return an array of the element hierarchy it
      * specifies. For example the key "x.y.z[@abc]" will result in [x, y, z].
      *
      * @param key the key to parse
      *
      * @return the elements in the key
      */
     protected static String[] parseElementNames(String key)
     {
         if (key == null)
         {
             return new String[]{};
         }
         else
         {
             // find the beginning of the attribute name
             int attStart = key.indexOf(ATTRIBUTE_START);

             if (attStart > -1)
             {
                 // remove the attribute part of the key
                 key = key.substring(0, attStart);
             }

             return StringUtils.split(key, NODE_DELIMITER);
         }
     }

     /**
      * Parse a property key and return the attribute name if it existst.
      *
      * @param key the key to parse
      *
      * @return the attribute name, or null if the key doesn't contain one
      */
     protected static String parseAttributeName(String key)
     {
         String name = null;

         if (key != null)
         {
             // find the beginning of the attribute name
             int attStart = key.indexOf(ATTRIBUTE_START);

             if (attStart > -1)
             {
                 // find the end of the attribute name
                 int attEnd = key.indexOf(ATTRIBUTE_END);
                 attEnd = attEnd > -1 ? attEnd : key.length();

                 name = key.substring(attStart + ATTRIBUTE_START.length(), attEnd);
             }
         }

         return name;
     }
 }
	/*
	* Copyright 2004 The Apache Software Foundation.
	*
	* 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.apache.commons.configuration;

	import java.io.File;
	import java.io.Reader;
	import java.io.StringWriter;
	import java.io.Writer;
	import java.net.URL;
	import java.util.ArrayList;
	import java.util.Iterator;
	import java.util.List;
	import javax.xml.parsers.DocumentBuilder;
	import javax.xml.parsers.DocumentBuilderFactory;
	import javax.xml.parsers.ParserConfigurationException;
	import javax.xml.transform.Result;
	import javax.xml.transform.Source;
	import javax.xml.transform.Transformer;
	import javax.xml.transform.TransformerException;
	import javax.xml.transform.TransformerFactory;
	import javax.xml.transform.dom.DOMSource;
	import javax.xml.transform.stream.StreamResult;

	import org.apache.commons.lang.StringUtils;
	import org.w3c.dom.Attr;
	import org.w3c.dom.CDATASection;
	import org.w3c.dom.CharacterData;
	import org.w3c.dom.Document;
	import org.w3c.dom.Element;
	import org.w3c.dom.NamedNodeMap;
	import org.w3c.dom.Node;
	import org.w3c.dom.NodeList;
	import org.w3c.dom.Text;
	import org.xml.sax.InputSource;

	/**
	* Reads a XML configuration file.
	*
	* To retrieve the value of an attribute of an element, use
	* <code>X.Y.Z[@attribute]</code>. The '@' symbol was chosen for consistency
	* with XPath.
	*
	* Setting property values will <b>NOT </b> automatically persist changes to
	* disk, unless <code>autoSave=true</code>.
	*
	* @since commons-configuration 1.0
	*
	* @author Jörg Schaible
	* @author <a href="mailto:kelvint@apache.org">Kelvin Tan </a>
	* @author <a href="mailto:dlr@apache.org">Daniel Rall </a>
	* @author Emmanuel Bourg
	* @version $Revision: 1.17 $, $Date: 2004/10/04 19:35:45 $
	*/
	public class XMLConfiguration extends AbstractFileConfiguration
	{
	// For conformance with xpath
	private static final String ATTRIBUTE_START = "[@";

	private static final String ATTRIBUTE_END = "]";

	/**
	* For consistency with properties files. Access nodes via an "A.B.C"
	* notation.
	*/
	private static final String NODE_DELIMITER = ".";

	/**
	* The XML document from our data source.
	*/
	private Document document;

	/**
	* If true, modifications are immediately persisted.
	*/
	private boolean autoSave = false;

	/**
	* Creates an empty XML configuration.
	*/
	public XMLConfiguration()
	{
	// build an empty document.
	DocumentBuilder builder = null;
	try
	{
	builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
	}
	catch (ParserConfigurationException e)
	{
	throw new ConfigurationRuntimeException(e.getMessage(), e);
	}

	document = builder.newDocument();
	document.appendChild(document.createElement("configuration"));
	}

	/**
	* Creates and loads the XML configuration from the specified resource.
	*
	* @param resource The name of the resource to load.
	*
	* @throws ConfigurationException Error while loading the XML file
	*/
	public XMLConfiguration(String resource) throws ConfigurationException
	{
	this.fileName = resource;
	url = ConfigurationUtils.locate(resource);
	load();
	}

	/**
	* Creates and loads the XML configuration from the specified file.
	*
	* @param file The XML file to load.
	* @throws ConfigurationException Error while loading the XML file
	*/
	public XMLConfiguration(File file) throws ConfigurationException
	{
	setFile(file);
	load();
	}

	/**
	* Creates and loads the XML configuration from the specified URL.
	*
	* @param url The location of the XML file to load.
	* @throws ConfigurationException Error while loading the XML file
	*/
	public XMLConfiguration(URL url) throws ConfigurationException
	{
	setURL(url);
	load();
	}

	/**
	* {@inheritDoc}
	*/
	public void load(Reader in) throws ConfigurationException
	{
	try
	{
	DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
	document = builder.parse(new InputSource(in));
	}
	catch (Exception e)
	{
	throw new ConfigurationException(e.getMessage(), e);
	}

	initProperties(document.getDocumentElement(), new StringBuffer());
	}

	/**
	* Loads and initializes from the XML file.
	*
	* @param element The element to start processing from. Callers should supply the root element of the document.
	* @param hierarchy
	*/
	private void initProperties(Element element, StringBuffer hierarchy)
	{
	StringBuffer buffer = new StringBuffer();
	NodeList list = element.getChildNodes();
	for (int i = 0; i < list.getLength(); i++)
	{
	Node node = list.item(i);
	if (node instanceof Element)
	{
	Element child = (Element) node;

	StringBuffer subhierarchy = new StringBuffer(hierarchy.toString());
	subhierarchy.append(child.getTagName());
	processAttributes(subhierarchy.toString(), child);
	initProperties(child, subhierarchy.append(NODE_DELIMITER));
	}
	else if (node instanceof CDATASection \|\| node instanceof Text)
	{
	CharacterData data = (CharacterData) node;
	buffer.append(data.getData());
	}
	}

	String text = buffer.toString().trim();
	if (text.length() > 0 && hierarchy.length() > 0)
	{
	super.addProperty(hierarchy.substring(0, hierarchy.length() - 1), text);
	}
	}

	/**
	* Helper method for constructing properties for the attributes of the given
	* XML element.
	*
	* @param hierarchy the actual hierarchy
	* @param element the actual XML element
	*/
	private void processAttributes(String hierarchy, Element element)
	{
	// Add attributes as x.y{ATTRIBUTE_START}att{ATTRIBUTE_END}
	NamedNodeMap attributes = element.getAttributes();
	for (int i = 0; i < attributes.getLength(); ++i)
	{
	Attr attr = (Attr) attributes.item(i);
	String attrName = hierarchy + ATTRIBUTE_START + attr.getName() + ATTRIBUTE_END;
	super.addProperty(attrName, attr.getValue());
	}
	}

	/**
	* Calls super method, and also ensures the underlying {@linkDocument} is
	* modified so changes are persisted when saved.
	*
	* @param name
	* @param value
	*/
	public void addProperty(String name, Object value)
	{
	super.addProperty(name, value);
	addXmlProperty(name, value);
	possiblySave();
	}

	Object getXmlProperty(String name)
	{
	// parse the key
	String[] nodes = parseElementNames(name);
	String attName = parseAttributeName(name);

	// get all the matching elements
	List children = findElementsForPropertyNodes(nodes);

	List properties = new ArrayList();
	if (attName == null)
	{
	// return text contents of elements
	Iterator cIter = children.iterator();
	while (cIter.hasNext())
	{
	Element child = (Element) cIter.next();
	// add non-empty strings
	String text = getChildText(child);
	if (StringUtils.isNotEmpty(text))
	{
	properties.add(text);
	}
	}
	}
	else
	{
	// return text contents of attributes
	Iterator cIter = children.iterator();
	while (cIter.hasNext())
	{
	Element child = (Element) cIter.next();
	if (child.hasAttribute(attName))
	{
	properties.add(child.getAttribute(attName));
	}
	}
	}

	switch (properties.size())
	{
	case 0:
	return null;
	case 1:
	return properties.get(0);
	default:
	return properties;
	}
	}

	/**
	* TODO Add comment.
	*
	* @param nodes
	* @return
	*/
	private List findElementsForPropertyNodes(String[] nodes)
	{
	List children = new ArrayList();
	List elements = new ArrayList();

	children.add(document.getDocumentElement());
	for (int i = 0; i < nodes.length; i++)
	{
	elements.clear();
	elements.addAll(children);
	children.clear();

	String eName = nodes[i];
	Iterator eIter = elements.iterator();
	while (eIter.hasNext())
	{
	Element element = (Element) eIter.next();
	NodeList list = element.getChildNodes();
	for (int j = 0; j < list.getLength(); j++)
	{
	Node node = list.item(j);
	if (node instanceof Element)
	{
	Element child = (Element) node;
	if (eName.equals(child.getTagName()))
	{
	children.add(child);
	}
	}
	}
	}
	}

	return children;
	}

	private static String getChildText(Node node)
	{
	// is there anything to do?
	if (node == null)
	{
	return null;
	}

	// concatenate children text
	StringBuffer str = new StringBuffer();
	Node child = node.getFirstChild();
	while (child != null)
	{
	short type = child.getNodeType();
	if (type == Node.TEXT_NODE)
	{
	str.append(child.getNodeValue());
	}
	else if (type == Node.CDATA_SECTION_NODE)
	{
	str.append(child.getNodeValue());
	}
	child = child.getNextSibling();
	}

	// return text value
	return StringUtils.trimToNull(str.toString());

	}

	private Element getChildElementWithName(String eName, Element element)
	{
	Element child = null;

	NodeList list = element.getChildNodes();
	for (int j = 0; j < list.getLength(); j++)
	{
	Node node = list.item(j);
	if (node instanceof Element)
	{
	child = (Element) node;
	if (eName.equals(child.getTagName()))
	{
	break;
	}
	child = null;
	}
	}
	return child;
	}

	/**
	* Adds the property value in our document tree.
	*
	* @param name The name of the element to set a value for.
	* @param value The value to set.
	*/
	private void addXmlProperty(String name, Object value)
	{
	// parse the key
	String[] nodes = parseElementNames(name);
	String attName = parseAttributeName(name);

	Element element = document.getDocumentElement();
	Element parent = element;

	for (int i = 0; i < nodes.length; i++)
	{
	if (element == null)
	{
	break;
	}
	parent = element;
	String eName = nodes[i];
	Element child = getChildElementWithName(eName, element);

	element = child;
	}

	Element child = document.createElement(nodes[nodes.length - 1]);
	parent.appendChild(child);
	if (attName == null)
	{
	CharacterData data = document.createTextNode(String.valueOf(value));
	child.appendChild(data);
	}
	else
	{
	child.setAttribute(attName, String.valueOf(value));
	}
	}

	/**
	* Calls super method, and also ensures the underlying {@link Document}is
	* modified so changes are persisted when saved.
	*
	* @param name The name of the property to clear.
	*/
	public void clearProperty(String name)
	{
	super.clearProperty(name);
	clearXmlProperty(name);
	possiblySave();
	}

	private void clearXmlProperty(String name)
	{
	// parse the key
	String[] nodes = parseElementNames(name);
	String attName = parseAttributeName(name);

	// get all the matching elements
	List children = findElementsForPropertyNodes(nodes);

	if (attName == null)
	{
	// remove children with no subelements
	Iterator cIter = children.iterator();
	while (cIter.hasNext())
	{
	Element child = (Element) cIter.next();

	// determine if child has subelments
	boolean hasSubelements = false;
	Node subchild = child.getFirstChild();
	while (subchild != null)
	{
	if (subchild.getNodeType() == Node.ELEMENT_NODE)
	{
	hasSubelements = true;
	break;
	}
	subchild = subchild.getNextSibling();
	}

	if (!hasSubelements)
	{
	// safe to remove
	if (!child.hasAttributes())
	{
	// remove entire node
	Node parent = child.getParentNode();
	parent.removeChild(child);
	}
	else
	{
	// only remove node contents
	subchild = child.getLastChild();
	while (subchild != null)
	{
	child.removeChild(subchild);
	subchild = child.getLastChild();
	}
	}
	}
	}
	}
	else
	{
	// remove attributes from children
	Iterator cIter = children.iterator();
	while (cIter.hasNext())
	{
	Element child = (Element) cIter.next();
	child.removeAttribute(attName);
	}
	}
	}

	/**
	* Save the configuration if the automatic persistence is enabled and a file
	* is specified.
	*/
	private void possiblySave()
	{
	if (autoSave && fileName != null)
	{
	try
	{
	save();
	}
	catch (ConfigurationException ce)
	{
	throw new ConfigurationRuntimeException("Failed to auto-save", ce);
	}
	}
	}

	/**
	* If true, changes are automatically persisted.
	*
	* @param autoSave
	*/
	public void setAutoSave(boolean autoSave)
	{
	this.autoSave = autoSave;
	}

	/**
	* {@inheritDoc}
	*/
	public void save(Writer writer) throws ConfigurationException
	{
	try
	{
	Transformer transformer = TransformerFactory.newInstance().newTransformer();
	Source source = new DOMSource(document);
	Result result = new StreamResult(writer);

	transformer.setOutputProperty("indent", "yes");
	transformer.transform(source, result);
	}
	catch (TransformerException e)
	{
	throw new ConfigurationException(e.getMessage(), e);
	}
	}

	public String toString()
	{
	StringWriter writer = new StringWriter();
	try
	{
	save(writer);
	}
	catch (ConfigurationException e)
	{
	e.printStackTrace();
	}
	return writer.toString();
	}

	/**
	* Parse a property key and return an array of the element hierarchy it
	* specifies. For example the key "x.y.z[@abc]" will result in [x, y, z].
	*
	* @param key the key to parse
	*
	* @return the elements in the key
	*/
	protected static String[] parseElementNames(String key)
	{
	if (key == null)
	{
	return new String[]{};
	}
	else
	{
	// find the beginning of the attribute name
	int attStart = key.indexOf(ATTRIBUTE_START);

	if (attStart > -1)
	{
	// remove the attribute part of the key
	key = key.substring(0, attStart);
	}

	return StringUtils.split(key, NODE_DELIMITER);
	}
	}

	/**
	* Parse a property key and return the attribute name if it existst.
	*
	* @param key the key to parse
	*
	* @return the attribute name, or null if the key doesn't contain one
	*/
	protected static String parseAttributeName(String key)
	{
	String name = null;

	if (key != null)
	{
	// find the beginning of the attribute name
	int attStart = key.indexOf(ATTRIBUTE_START);

	if (attStart > -1)
	{
	// find the end of the attribute name
	int attEnd = key.indexOf(ATTRIBUTE_END);
	attEnd = attEnd > -1 ? attEnd : key.length();

	name = key.substring(attStart + ATTRIBUTE_START.length(), attEnd);
	}
	}

	return name;
	}
	}