Macro to get the content of a unique XML child element. - Java XML

Java examples for XML:XML Element Child

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Description

Macro to get the content of a unique XML child element.

Demo Code

/*//from www. j  a v  a  2s  .c  om
 * 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 com.java2s;
import java.util.ArrayList;
import java.util.Iterator;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class Main {
    /**
     * 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));
    }

    /**
     * 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();
    }

    /**
     * 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");
        }
    }

    /**
     * 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();
    }
}

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