Macro to get the content of a unique child element. : DOM Element « XML « Java

1. Java
2. XML
3. DOM Element

Macro to get the content of a unique child element.

    

import java.util.ArrayList;
import java.util.Iterator;

import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/*
  * JBoss, Home of Professional Open Source
  * Copyright 2005, JBoss Inc., and individual contributors as indicated
  * by the @authors tag. See the copyright.txt in the distribution for a
  * full listing of individual contributors.
  *
  * This is free software; you can redistribute it and/or modify it
  * under the terms of the GNU Lesser General Public License as
  * published by the Free Software Foundation; either version 2.1 of
  * the License, or (at your option) any later version.
  *
  * This software 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 software; if not, write to the Free
  * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
  */

public class Utils {
  /**
   * 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();
     String result = "";
     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 += children.item(i).getNodeValue();
        }
        else if( children.item(i).getNodeType() == Node.COMMENT_NODE )
        {
           // Ignore comment nodes
        }
     }
     return result.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<Element> goodChildren = getChildrenByTagName(element, tagName);

     if (goodChildren != null && goodChildren.hasNext()) {
        Element child = 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<Element> 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<Element> goodChildren = new ArrayList<Element>();
     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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