/*
* 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.domapi.XPathEvaluatorImpl;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.xpath.XPathEvaluator;
import org.w3c.dom.xpath.XPathNSResolver;
import org.w3c.dom.xpath.XPathResult;
import org.xml.sax.InputSource;
/**
* Very basic utility for applying the DOM L3 XPath API (currently in Last Call)
* 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 ApplyXPathDOM foo.xml /
* java ApplyXPathDOM foo.xml /doc/name[1]/@last
*
*<p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.</p>
* @see XPathEvaluator
*
*/
public class ApplyXPathDOM
{
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 DOM L3 XPath API to apply the xpath expression to the doc.
System.out.println("Querying DOM using "+xpath);
// Create an XPath evaluator and pass in the document.
XPathEvaluator evaluator = new XPathEvaluatorImpl(doc);
XPathNSResolver resolver = evaluator.createNSResolver(doc);
// Evaluate the xpath expression
XPathResult result = (XPathResult)evaluator.evaluate(xpath, doc, resolver, XPathResult.UNORDERED_NODE_ITERATOR_TYPE, null);
// Serialize the found nodes to System.out.
System.out.println("<output>");
Node n;
while ((n = result.iterateNext())!= 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 ApplyXPathDOM filename.xml xpath\n"
+ "Reads filename.xml and applies the xpath; prints the nodelist found.");
return;
}
ApplyXPathDOM app = new ApplyXPathDOM();
app.doMain(args);
}
} // end of class ApplyXPathDOM