xmlutils.java

这是一个用java和xml编写的流媒体服务器管理软件

/*
 * ====================================================================
 * The Vovida Software License, Version 1.0
 * 
 * Copyright (c) 2000 Vovida Networks, Inc.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in
 * the documentation and/or other materials provided with the
 * distribution.
 * 
 * 3. The names "VOCAL", "Vovida Open Communication Application Library",
 * and "Vovida Open Communication Application Library (VOCAL)" must
 * not be used to endorse or promote products derived from this
 * software without prior written permission. For written
 * permission, please contact [e-mail].
 * 
 * 4. Products derived from this software may not be called "VOCAL", nor
 * may "VOCAL" appear in their name, without prior written
 * permission of Vovida Networks, Inc.
 * 
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
 * NON-INFRINGEMENT ARE DISCLAIMED.  IN NO EVENT SHALL VOVIDA
 * NETWORKS, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT DAMAGES
 * IN EXCESS OF $1,000, NOR FOR ANY INDIRECT, INCIDENTAL, SPECIAL,
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 * 
 * ====================================================================
 * 
 * This software consists of voluntary contributions made by Vovida
 * Networks, Inc. and many individuals on behalf of Vovida Networks,
 * Inc.  For more information on Vovida Networks, Inc., please see
 * <http://www.vovida.org/>.
 * 
 */

package vocal.data;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.*;
import org.xml.sax.*;

/**
 * $RCSfile$
 * 
 * @author $Author$, $Date$
 * @version $Revision$
 */
public class XMLUtils
{

  // used for traverse method
  private StringBuffer traverseBuffer;

  /**
   * 
   */
  public static String getAttribute(Element parent, String childName, 
          String attributeName) throws NoSuchNodeException
  {
    NodeList nodes = parent.getElementsByTagName(childName);

    if (nodes.getLength() < 1)
    {
      throw new NoSuchNodeException(childName + " of parent " 
              + parent.getTagName() + " does not exist");
    }

    Element child = (Element) (nodes.item(0));

    return child.getAttribute(attributeName);
  }

  // returns first child of this name

  /**
   * 
   */
  public static Element getChildByName(Element parent, 
          String name) throws NoSuchNodeException
  {
    NodeList nodes = parent.getChildNodes();
    Node node = null;

    for (int i = 0; i < nodes.getLength(); i++)
    {
      node = nodes.item(i);

      if (node.getNodeName().equals(name))
      {
        return (Element) node;
      }
    }

    throw new NoSuchNodeException("Child " + name + " of parent " 
            + parent.getNodeName() + " not found");
  }

  /**
   * 
   * @param parent
   * @param childName
   * @param text
   * 
   * @throws NoSuchNodeException
   * @throws NotTextNodeException
   */
  public static void setContent(Element parent, String childName, 
          String text) throws NoSuchNodeException, NotTextNodeException
  {
    Element child = getChildByName(parent, childName);

    setContent(child, text);

  }

  /**
   * 
   * @param contentNode
   * @param text
   * 
   * @throws NoSuchNodeException
   * @throws NotTextNodeException
   */
  public static void setContent(Element contentNode, 
          String text) throws NoSuchNodeException, NotTextNodeException
  {
    NodeList nl = contentNode.getChildNodes();

    if (nl.getLength() == 0)
    {

      // there is no text associated with this node yet.
      throw new NoSuchNodeException(contentNode.getTagName() 
              + " has no text");
    }

    Node textNode = nl.item(0);

    try
    {
      ((CharacterData) textNode).setData(text);
    }
    catch (ClassCastException e)
    {
      throw new NotTextNodeException(contentNode.getTagName() 
              + " not a text node");
    }
  }

  /**
   * 
   */
  public static String getContent(Element contentNode) 
    throws NotTextNodeException
  {
    NodeList nl = contentNode.getChildNodes();
    Node textNode = nl.item(0);

    if (textNode == null)
    {
      return "";
    }

    try
    {
      return ((CharacterData) textNode).getData();
    }
    catch (ClassCastException e)
    {
      throw new NotTextNodeException(contentNode.getTagName() 
              + " not a text node");
    }
  }

  /**
   * 
   */
  public static String getContent(Element parent, 
          String childName) throws NoSuchNodeException, NotTextNodeException
  {
    Element child = getChildByName(parent, childName);

    return getContent(child);
  }

  /**
   * We should be able to substitute the xsl identity function for this.
   */
  public String buildXMLString(Node node)
  {
    traverseBuffer = new StringBuffer();

    return traverse(node);
  }

  /**
   * 
   */
  private String traverse(Node node)
  {

    // is there anything to do?
    if (node == null)
    {
      return "";
    }

    int type = node.getNodeType();

    switch (type)
    {

      // traverse document
      case Node.DOCUMENT_NODE:
      {
        traverse(((Document) node).getDocumentElement());

        break;
      }

      // traverse document fragment
      case Node.DOCUMENT_FRAGMENT_NODE:
      {
        traverse(node.getFirstChild());

        break;
      }

      // traverse element with attributes
      case Node.ELEMENT_NODE:
      {
        traverseBuffer.append('<');
        traverseBuffer.append(node.getNodeName());

        NamedNodeMap attrs = node.getAttributes();

        for (int i = 0; i < attrs.getLength(); i++)
        {
          Node attr = attrs.item(i);

          traverseBuffer.append(' ');
          traverseBuffer.append(attr.getNodeName());
          traverseBuffer.append("=\"");
          traverseBuffer.append(attr.getNodeValue());
          traverseBuffer.append('"');
        }

        traverseBuffer.append(">");

        NodeList children = node.getChildNodes();

        if (children != null)
        {
          int len = children.getLength();

          for (int i = 0; i < len; i++)
          {
            traverse(children.item(i));
          }
        }

        break;
      }

      // traverse text
      case Node.TEXT_NODE:
      {
        traverseBuffer.append(node.getNodeValue().trim());

        break;
      }
    }

    if (type == Node.ELEMENT_NODE)
    {
      traverseBuffer.append("</");
      traverseBuffer.append(node.getNodeName());
      traverseBuffer.append(">\n");
    }

    return new String(traverseBuffer);

  }     // end of traverse

}