Parsing XML file using Xpath in jdk1.4

[ziggy]

The following code is used to extract a specific element's value using xpath in jdk1.5

import java.io.IOException;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
import javax.xml.parsers.*;
import javax.xml.xpath.*;

public class XPathExample {

  public static void main(String[] args) 
   throws ParserConfigurationException, SAXException, 
          IOException, XPathExpressionException {

    DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
    domFactory.setNamespaceAware(true); // never forget this!
    DocumentBuilder builder = domFactory.newDocumentBuilder();
    Document doc = builder.parse("c:\\temp\\books.xml");

    XPathFactory factory = XPathFactory.newInstance();
    XPath xpath = factory.newXPath();
    XPathExpression expr 
     = xpath.compile("//book[author='Neal Stephenson']/title/text()");

    Object result = expr.evaluate(doc, XPathConstants.NODESET);
    NodeList nodes = (NodeList) result;
    for (int i = 0; i < nodes.getLength(); i++) {
        System.out.println(nodes.item(i).getNodeValue()); 
    }

  }

}

This uses xpath to extract all books title where the author is Neal Stephenson from the following xml

<inventory>
<book year="2000">
    <title>Snow Crash</title>
    <author>Neal Stephenson</author>
    <publisher>Spectra</publisher>
    <isbn>0553380958</isbn>
    <price>14.95</price>
</book>

<book year="2005">
    <title>Burning Tower</title>
    <author>Larry Niven</author>
    <author>Jerry Pournelle</author>
    <publisher>Pocket</publisher>
    <isbn>0743416910</isbn>
    <price>5.99</price>
</book>

<book year="1995">
    <title>Zodiac</title>
    <author>Neal Stephenson</author>
    <publisher>Spectra</publisher>
    <isbn>0553573862</isbn>
    <price>7.50</price>
</book>
</inventory>

Now this works fine on JDK5 but i am using jdk 1.4 Can this be converted to the java 1.4 equivalent?

All i am trying to do is extract a value from an xml element. For example, in the above xml, i just want something that is the equivalent of getElementByTag("title").

According to a response i got from another site [for some reason the forum is not allowing me to post the link], JAXP can be downloaded separately. This has confused me a bit as i read somewhere else that JAXP is included in jdk1.4

Could someone please clarify this please and let me know what exactly i need to do to be able to use xpath in jdk1.4

[eRaaaa]

Could someone please clarify this please and let me know what exactly i need to do to be able to use xpath in jdk1.4

I am not sure what exactly your question is now, but the javax.xml.xpath package is available since 1.5 see : javax.xml.xpath (Java 2 Platform SE 5.0)

To use XPath in 1.4 you could use JDOM

import java.util.List;
import org.jdom.Document;
import org.jdom.Text;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;

//.....
	public static void main(String[] args) throws Exception {
		Document doc = new SAXBuilder().build("c:\\temp\\books.xml");
		List nameList = XPath.selectNodes(doc, "//book[author='Neal Stephenson']/title/text()");
		for (int i = 0; i < nameList.size(); i++) {
			System.out.println(((Text)nameList.get(i)).getValue());
		}
	}

[ziggy]

The reason it is confusing is that there is conflicting information as to whether xpath is possible in jdk 1.4. For example, have a look at this page JAXP: Updating and Using — Java.net

At the very bottom of the page there is a section that mentions that JAXP is included in 1.4 but somehow not accessible via the normal way. (At least thats how i interpreted it)

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What is the difference between JDOM and JAXP?

[Fubarable]

What is the difference between JDOM and JAXP?

JDOM: JDOM - Wikipedia, the free encyclopedia

JAXP: Java API for XML Processing - Wikipedia, the free encyclopedia

[ziggy]

Ok i have tried this with JDOM because i think messing around with libraries in teh endorsed directory is not safe. I tried to parse the same xml file shown above with the following code using JDOM

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;
import org.jdom.Document;
import org.jdom.Element;
import org.xml.sax.SAXException;

public class XPathExample {

  public static void main(String[] args) 
   throws ParserConfigurationException, SAXException, 
          IOException, Exception {
	  
	// import org.jdom.Document;
	// import org.jdom.Element;
	// import org.jdom.JDOMException;
	// import org.jdom.input.SAXBuilder;
	// import org.jdom.xpath.XPath;
	 String fn = "c:\\temp\\books.xml";
	 FileInputStream in = new FileInputStream(fn);
	 SAXBuilder builder = new SAXBuilder();
	 Document doc = builder.build(in);
	 in.close();
	 
	 XPath xpath = XPath.newInstance("//book[author='Neal Stephenson']/title/text()");
	 List list = xpath.selectNodes(doc);
	 for (Iterator iter = list.iterator(); iter.hasNext();) {
	  Element elem = (Element) iter.next();
	   
	  String childText = elem.getChild("child").getTextTrim();
	  String text = elem.getTextTrim();
	  
	  System.out.println("Value : " + text);
	 }	 
  }
}

But it fails with a class cast exception at the line with

Element elem = (Element) iter.next();

[eRaaaa]

In your XPath you are selecting text() at the end, so iter.next() will return a Text-object, not an element, looking at my code!

[ziggy]

I am not sure what exactly your question is now, but the javax.xml.xpath package is available since 1.5 see : javax.xml.xpath (Java 2 Platform SE 5.0)

To use XPath in 1.4 you could use JDOM

import java.util.List;
import org.jdom.Document;
import org.jdom.Text;
import org.jdom.input.SAXBuilder;
import org.jdom.xpath.XPath;

//.....
	public static void main(String[] args) throws Exception {
		Document doc = new SAXBuilder().build("c:\\temp\\books.xml");
		List nameList = XPath.selectNodes(doc, "//book[author='Neal Stephenson']/title/text()");
		for (int i = 0; i < nameList.size(); i++) {
			System.out.println(((Text)nameList.get(i)).getValue());
		}
	}

In your XPath you are selecting text() and the end, so iter.next() will return a Text-object, not an element, looking at my code!

I am still learining this so please excuse the dumb questions :)
The above code was based on the example @ Note to self: parse xml with JDOM and Xpath