Hibernate example source code file (XmlHelper.java)

This example Hibernate source code file (XmlHelper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

arraylist, dom, element, element, exception, exception, iterator, iterator, node, nodelist, string, string, stringbuilder, util, xmlhelper

The Hibernate XmlHelper.java source code

/*
 * Copyright (c) 2009, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.ejb.packaging;
import java.util.ArrayList;
import java.util.Iterator;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * A utility class to cover up the rough bits of xml parsing
 *
 * @author <a href="mailto:chris@kimptoc.net">Chris Kimpton
 */
public final class XmlHelper {
	private XmlHelper() {
	}

	/**
	 * Returns an iterator over the children of the given element with
	 * the given tag name.
	 *
	 * @param element The parent element
	 * @param tagName The name of the desired child
	 * @return An interator of children or null if element is null.
	 */
	public static Iterator getChildrenByTagName(
			Element element,
			String tagName) {
		if ( element == null ) return null;
		// getElementsByTagName gives the corresponding elements in the whole
		// descendance. We want only children

		NodeList children = element.getChildNodes();
		ArrayList goodChildren = new ArrayList();
		for ( int i = 0; i < children.getLength() ; i++ ) {
			Node currentChild = children.item( i );
			if ( currentChild.getNodeType() == Node.ELEMENT_NODE &&
					( (Element) currentChild ).getTagName().equals( tagName ) ) {
				goodChildren.add( (Element) currentChild );
			}
		}
		return goodChildren.iterator();
	}

	/**
	 * Gets the child of the specified element having the specified unique
	 * name.  If there are more than one children elements with the same name
	 * and exception is thrown.
	 *
	 * @param element The parent element
	 * @param tagName The name of the desired child
	 * @return The named child.
	 * @throws Exception Child was not found or was not unique.
	 */
	public static Element getUniqueChild(Element element, String tagName)
			throws Exception {
		Iterator goodChildren = getChildrenByTagName( element, tagName );

		if ( goodChildren != null && goodChildren.hasNext() ) {
			Element child = (Element) goodChildren.next();
			if ( goodChildren.hasNext() ) {
				throw new Exception
						( "expected only one " + tagName + " tag" );
			}
			return child;
		}
		else {
			throw new Exception
					( "expected one " + tagName + " tag" );
		}
	}

	/**
	 * Gets the child of the specified element having the
	 * specified name. If the child with this name doesn't exist
	 * then null is returned instead.
	 *
	 * @param element the parent element
	 * @param tagName the name of the desired child
	 * @return either the named child or null
	 */
	public static Element getOptionalChild(Element element, String tagName)
			throws Exception {
		return getOptionalChild( element, tagName, null );
	}

	/**
	 * Gets the child of the specified element having the
	 * specified name. If the child with this name doesn't exist
	 * then the supplied default element is returned instead.
	 *
	 * @param element		the parent element
	 * @param tagName		the name of the desired child
	 * @param defaultElement the element to return if the child
	 *                       doesn't exist
	 * @return either the named child or the supplied default
	 */
	public static Element getOptionalChild(
			Element element,
			String tagName,
			Element defaultElement) throws Exception {
		Iterator goodChildren = getChildrenByTagName( element, tagName );

		if ( goodChildren != null && goodChildren.hasNext() ) {
			Element child = (Element) goodChildren.next();
			if ( goodChildren.hasNext() ) {
				throw new Exception
						( "expected only one " + tagName + " tag" );
			}
			return child;
		}
		else {
			return defaultElement;
		}
	}

	/**
	 * Get the content of the given element.
	 *
	 * @param element The element to get the content for.
	 * @return The content of the element or null.
	 */
	public static String getElementContent(final Element element)
			throws Exception {
		return getElementContent( element, null );
	}

	/**
	 * Get the content of the given element.
	 *
	 * @param element	The element to get the content for.
	 * @param defaultStr The default to return when there is no content.
	 * @return The content of the element or the default.
	 */
	public static String getElementContent(Element element, String defaultStr)
			throws Exception {
		if ( element == null ) {
			return defaultStr;
		}

		NodeList children = element.getChildNodes();
		StringBuilder result = new StringBuilder("");
		for ( int i = 0; i < children.getLength() ; i++ ) {
			if ( children.item( i ).getNodeType() == Node.TEXT_NODE ||
					children.item( i ).getNodeType() == Node.CDATA_SECTION_NODE ) {
				result.append( children.item( i ).getNodeValue() );
			}
//			else if ( children.item( i ).getNodeType() == Node.COMMENT_NODE ) {
//				// Ignore comment nodes
//			}
		}
		return result.toString().trim();
	}

	/**
	 * Macro to get the content of a unique child element.
	 *
	 * @param element The parent element.
	 * @param tagName The name of the desired child.
	 * @return The element content or null.
	 */
	public static String getUniqueChildContent(
			Element element,
			String tagName) throws Exception {
		return getElementContent( getUniqueChild( element, tagName ) );
	}

	/**
	 * Macro to get the content of an optional child element.
	 *
	 * @param element The parent element.
	 * @param tagName The name of the desired child.
	 * @return The element content or null.
	 */
	public static String getOptionalChildContent(
			Element element,
			String tagName) throws Exception {
		return getElementContent( getOptionalChild( element, tagName ) );
	}

	public static boolean getOptionalChildBooleanContent(Element element, String name) throws Exception {
		Element child = getOptionalChild( element, name );
		if ( child != null ) {
			String value = getElementContent( child ).toLowerCase();
			return value.equals( "true" ) || value.equals( "yes" );
		}

		return false;
	}


}