XPathProcessorImpl


1   /*****************************************************************************
2    * Copyright (C) The Apache Software Foundation. All rights reserved.        *
3    * ------------------------------------------------------------------------- *
4    * This software is published under the terms of the Apache Software License *
5    * version 1.1, a copy of which has been included  with this distribution in *
6    * the LICENSE.txt file.                                                         *
7    *****************************************************************************/
8   package org.apache.avalon.excalibur.xml.xpath;
9   
10  import org.apache.avalon.framework.thread.ThreadSafe;
11  import org.apache.avalon.framework.component.Component;
12  import org.apache.avalon.framework.logger.AbstractLoggable;
13  import org.w3c.dom.Node  ;
14  import org.w3c.dom.NodeList  ;
15  import org.apache.xpath.XPathAPI;
16  
17  /**
18   * This class defines the implementation of the {@link XPathProcessor}
19   * component.
20   *
21   * To configure it, add the following lines in the
22   * <file>cocoon.xconf</file> file:
23   *
24   * <pre>
25   * &lt;xpath-processor class="org.apache.cocoon.components.xpath.XPathProcessorImpl"&gt;
26   * &lt;/xpath-processor&gt;
27   * </pre>
28   *
29   * @author <a HREF="mailto:dims@yahoo.com">Davanum Srinivas</a>
30   * @version CVS $Revision: 1.5 $ $Date: 2002/01/08 07:57:40 $ $Author: cziegeler $
31   */
32  public class XPathProcessorImpl
33    extends AbstractLoggable
34    implements XPathProcessor, ThreadSafe
35  {
36      /**
37       * Use an XPath string to select a single node. XPath namespace
38       * prefixes are resolved from the context node, which may not
39       * be what you want (see the next method).
40       *
41       * @param contextNode The node to start searching from.
42       * @param str A valid XPath string.
43       * @return The first node found that matches the XPath, or null.
44       */
45      public Node   selectSingleNode(Node   contextNode, String   str)
46      {
47          try {
48              return XPathAPI.selectSingleNode(contextNode, str);
49          } catch (javax.xml.transform.TransformerException   e){
50              return null;
51          }
52      }
53  
54        /**
55         *  Use an XPath string to select a nodelist.
56         *  XPath namespace prefixes are resolved from the contextNode.
57         *
58         *  @param contextNode The node to start searching from.
59         *  @param str A valid XPath string.
60         *  @return A NodeList, should never be null.
61         */
62      public NodeList   selectNodeList(Node   contextNode, String   str)
63      {
64        try {
65            return XPathAPI.selectNodeList(contextNode, str);
66        } catch (javax.xml.transform.TransformerException   e){
67            return new NodeList  (){
68                public Node   item(int index) { return null;}
69                public int getLength(){return 0;}
70            };
71        }
72      }
73  }
74
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