content: // Namespaces.java - Analyze namespace nodes in a DOM tree
  
  /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 mf.org.apache.xml.resolver.helpers;
  
  import mf.org.w3c.dom.Element;
  import mf.org.w3c.dom.Node;
  
  /**
   * Static Namespace query methods.
   * <p/>
   * <p>This class defines a set of static methods that can be called
   * to analyze the namespace properties of DOM nodes.</p>
   *
   * @author Norman Walsh
   *         <a href="mailto:Norman.Walsh@Sun.COM">Norman.Walsh@Sun.COM</a>
   * @version 1.0
   */
  public class Namespaces {
      /**
       * Returns the "prefix" part of a QName or the empty string (not
       * null) if the name has no prefix.
       *
       * @param element The QName of an element.
       * @return The prefix part of the element name.
       */
      public static String getPrefix(Element element) {
          String name = element.getTagName();
          String prefix = "";
  
          if (name.indexOf(':') > 0) {
              prefix = name.substring(0, name.indexOf(':'));
          }
  
          return prefix;
      }
  
      /**
       * Returns the "localname" part of a QName, which is the whole
       * name if it has no prefix.
       *
       * @param element The QName of an element.
       * @return The local part of a QName.
       */
      public static String getLocalName(Element element) {
          String name = element.getTagName();
  
          if (name.indexOf(':') > 0) {
              name = name.substring(name.indexOf(':') + 1);
          }
  
          return name;
      }
  
      /**
       * Returns the namespace URI for the specified prefix at the
       * specified context node.
       *
       * @param node   The context node.
       * @param prefix The prefix.
       * @return The namespace URI associated with the prefix, or
       * null if no namespace declaration exists for the prefix.
       */
      public static String getNamespaceURI(Node node, String prefix) {
          if (node == null || node.getNodeType() != Node.ELEMENT_NODE) {
              return null;
          }
  
          if (prefix.equals("")) {
              if (((Element) node).hasAttribute("xmlns")) {
                  return ((Element) node).getAttribute("xmlns");
              }
          } else {
              String nsattr = "xmlns:" + prefix;
              if (((Element) node).hasAttribute(nsattr)) {
                  return ((Element) node).getAttribute(nsattr);
              }
          }
  
          return getNamespaceURI(node.getParentNode(), prefix);
      }
  
      /**
       * Returns the namespace URI for the namespace to which the
       * element belongs.
       *
       * @param element The element.
       * @return The namespace URI associated with the namespace of the
       * element, or null if no namespace declaration exists for it.
       */
      public static String getNamespaceURI(Element element) {
          String prefix = getPrefix(element);
          return getNamespaceURI(element, prefix);
      }
  }
  