code: /*
   * 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.
   */
  /*
   * $Id$
   */
  // This file uses 4 space indents, no tabs.
  
  import java.io.FileInputStream;
  import java.io.OutputStreamWriter;
  
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.transform.OutputKeys;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  
  import org.apache.xpath.XPathAPI;
  import org.w3c.dom.Document;
  import org.w3c.dom.Node;
  import org.w3c.dom.traversal.NodeIterator;
  import org.xml.sax.InputSource;
  
  /**
   *  Very basic utility for applying an XPath epxression to an xml file and printing information
   /  about the execution of the XPath object and the nodes it finds.
   *  Takes 2 arguments:
   *     (1) an xml filename
   *     (2) an XPath expression to apply to the file
   *  Examples:
   *     java ApplyXPath foo.xml /
   *     java ApplyXPath foo.xml /doc/name[1]/@last
   * @see XPathAPI
   */
  public class ApplyXPath
  {
    protected String filename = null;
    protected String xpath = null;
  
    /** Process input args and execute the XPath.  */
    public void doMain(String[] args)
      throws Exception
    {
      filename = args[0];
      xpath = args[1];
  
      if ((filename != null) && (filename.length() > 0)
          && (xpath != null) && (xpath.length() > 0))
      {
        // Tell that we're loading classes and parsing, so the time it 
        // takes to do this doesn't get confused with the time to do 
        // the actual query and serialization.
        System.out.println("Loading classes, parsing "+filename+", and setting up serializer");
        
        // Set up a DOM tree to query.
        InputSource in = new InputSource(new FileInputStream(filename));
        DocumentBuilderFactory dfactory = DocumentBuilderFactory.newInstance();
        dfactory.setNamespaceAware(true);
        Document doc = dfactory.newDocumentBuilder().parse(in);
        
        // Set up an identity transformer to use as serializer.
        Transformer serializer = TransformerFactory.newInstance().newTransformer();
        serializer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
  
        // Use the simple XPath API to select a nodeIterator.
        System.out.println("Querying DOM using "+xpath);
        NodeIterator nl = XPathAPI.selectNodeIterator(doc, xpath);
  
        // Serialize the found nodes to System.out.
        System.out.println("<output>");
                    
        Node n;
        while ((n = nl.nextNode())!= null)
        {         
  	if (isTextNode(n)) {
  	    // DOM may have more than one node corresponding to a 
  	    // single XPath text node.  Coalesce all contiguous text nodes
  	    // at this level
  	    StringBuffer sb = new StringBuffer(n.getNodeValue());
  	    for (
  	      Node nn = n.getNextSibling(); 
  	      isTextNode(nn);
  	      nn = nn.getNextSibling()
  	    ) {
  	      sb.append(nn.getNodeValue());
  	    }
  	    System.out.print(sb);
  	}
  	else {
           serializer.transform(new DOMSource(n), new StreamResult(new OutputStreamWriter(System.out)));
  	}
          System.out.println();
        }
        System.out.println("</output>");
      }
      else
      {
        System.out.println("Bad input args: " + filename + ", " + xpath);
      }
    }
    
    /** Decide if the node is text, and so must be handled specially */
    static boolean isTextNode(Node n) {
      if (n == null)
        return false;
      short nodeType = n.getNodeType();
      return nodeType == Node.CDATA_SECTION_NODE || nodeType == Node.TEXT_NODE;
    }
  
    /** Main method to run from the command line.    */
    public static void main (String[] args)
      throws Exception
    {
      if (args.length != 2)
      {
        System.out.println("java ApplyXPath filename.xml xpath\n"
                           + "Reads filename.xml and applies the xpath; prints the nodelist found.");
        return;
      }
          
      ApplyXPath app = new ApplyXPath();
      app.doMain(args);
    }	
    
  } // end of class ApplyXPath
  
  