a simple java program that test xpath

java xml.XpathMain test.xml //column

package xml;

import java.io.StringWriter;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.TransformerFactoryConfigurationError;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class XpathMain {


	public static void main(String[] args) throws Exception {
		if (args.length<2) {
			System.out.println("Usage: XpathMain xmlfile xpath");
			System.exit(1);
		}
		
		String xmlfile=args[0];
		String xpathStr=args[1];
		System.out.println("xmlfile:"+xmlfile+", xpath="+xpathStr+"\n");
		
	    DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
	    domFactory.setNamespaceAware(true); // never forget this!
	    DocumentBuilder builder = domFactory.newDocumentBuilder();
	    Document doc = builder.parse(xmlfile);
	    
	    XPathFactory factory = XPathFactory.newInstance();
	    XPath xpath = factory.newXPath();
	    XPathExpression expr 
	    	= xpath.compile(xpathStr);
	    
	    Object result = expr.evaluate(doc, XPathConstants.NODESET);
	    NodeList nodes = (NodeList) result;
	    for (int i = 0; i < nodes.getLength(); i++) {
	    	Node node=nodes.item(i);
	        System.out.println(dumpNode(node)); 
	    }

	}
	
	public static String dumpNode(Node node) 
		throws TransformerFactoryConfigurationError, TransformerException {
		
		Transformer transformer = TransformerFactory.newInstance().newTransformer();
		transformer.setOutputProperty(OutputKeys.INDENT, "yes");

		StreamResult result = new StreamResult(new StringWriter());
		DOMSource source = new DOMSource(node);
		transformer.transform(source, result);

		String xmlString = result.getWriter().toString();
		return xmlString;
	}

}