DomUtils.java Source code

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Here is the source code for DomUtils.java

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/*
 * Copyright 2002-2007 the original author or authors.
 *
 * 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.
 */

import java.util.ArrayList;
import java.util.List;

import org.w3c.dom.CharacterData;
import org.w3c.dom.Comment;
import org.w3c.dom.Element;
import org.w3c.dom.EntityReference;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
 * Convenience methods for working with the DOM API,
 * in particular for working with DOM Nodes and DOM Elements.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @author Costin Leau
 * @since 1.2
 * @see org.w3c.dom.Node
 * @see org.w3c.dom.Element
 */
public abstract class DomUtils {

    /**
     * Retrieve all child elements of the given DOM element that match
     * the given element name. Only look at the direct child level of the
     * given element; do not go into further depth (in contrast to the
     * DOM API's <code>getElementsByTagName</code> method).
     * @param ele the DOM element to analyze
     * @param childEleName the child element name to look for
     * @return a List of child <code>org.w3c.dom.Element</code> instances
     * @see org.w3c.dom.Element
     * @see org.w3c.dom.Element#getElementsByTagName
     */
    public static List getChildElementsByTagName(Element ele, String childEleName) {
        NodeList nl = ele.getChildNodes();
        List childEles = new ArrayList();
        for (int i = 0; i < nl.getLength(); i++) {
            Node node = nl.item(i);
            if (node instanceof Element && nodeNameEquals(node, childEleName)) {
                childEles.add(node);
            }
        }
        return childEles;
    }

    /**
     * Utility method that returns the first child element
     * identified by its name.
     * @param ele the DOM element to analyze
     * @param childEleName the child element name to look for
     * @return the <code>org.w3c.dom.Element</code> instance,
     * or <code>null</code> if none found
     */
    public static Element getChildElementByTagName(Element ele, String childEleName) {
        NodeList nl = ele.getChildNodes();
        for (int i = 0; i < nl.getLength(); i++) {
            Node node = nl.item(i);
            if (node instanceof Element && nodeNameEquals(node, childEleName)) {
                return (Element) node;
            }
        }
        return null;
    }

    /**
     * Utility method that returns the first child element value
     * identified by its name.
     * @param ele the DOM element to analyze
     * @param childEleName the child element name to look for
     * @return the extracted text value,
     * or <code>null</code> if no child element found
     */
    public static String getChildElementValueByTagName(Element ele, String childEleName) {
        Element child = getChildElementByTagName(ele, childEleName);
        return (child != null ? getTextValue(child) : null);
    }

    /**
     * Namespace-aware equals comparison. Returns <code>true</code> if either
     * {@link Node#getLocalName} or {@link Node#getNodeName} equals <code>desiredName</code>,
     * otherwise returns <code>false</code>.
     */
    public static boolean nodeNameEquals(Node node, String desiredName) {
        return (desiredName.equals(node.getNodeName()) || desiredName.equals(node.getLocalName()));
    }

    /**
     * Extract the text value from the given DOM element, ignoring XML comments.
     * <p>Appends all CharacterData nodes and EntityReference nodes
     * into a single String value, excluding Comment nodes.
     * @see CharacterData
     * @see EntityReference
     * @see Comment
     */
    public static String getTextValue(Element valueEle) {
        StringBuffer value = new StringBuffer();
        NodeList nl = valueEle.getChildNodes();
        for (int i = 0; i < nl.getLength(); i++) {
            Node item = nl.item(i);
            if ((item instanceof CharacterData && !(item instanceof Comment)) || item instanceof EntityReference) {
                value.append(item.getNodeValue());
            }
        }
        return value.toString();
    }

}