java使用XPath解析xml

<widgets>
<widget value="widgetValue">widText</widget>
</widgets>

public static void examineXmlFile(String path) throws Exception {
        DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
        domFactory.setNamespaceAware(true); // never forget this!
        DocumentBuilder builder = domFactory.newDocumentBuilder();
        Document doc = builder.parse(path);

        XPathFactory factory = XPathFactory.newInstance();
        XPath xpath = factory.newXPath();
        XPathExpression expr = xpath.compile("//node/@id");

        Object result = expr.evaluate(doc,XPathConstants.NODESET);

        NodeList nodes = (NodeList) result;
        for (int i = 0; i < nodes.getLength(); i++) {
            Node n = nodes.item(i);
            System.out.println(nodes.item(i).getNodeValue());
        }
    }

package util.xml;
import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import com.sun.org.apache.xpath.internal.NodeSet;
public class ReadXMLbyXPath {
  public static void main(String[] arg ) throws XPathExpressionException,ParserConfigurationException,SAXException,IOException
  {
     // parse the XML as a W3C Document
     DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
     Document document = builder.parse(new File("E:/workspace/Java-Util/src/util/xml/widgets.xml"));
     XPath xpath = XPathFactory.newInstance().newXPath();
     String expression = "/widgets/widget";
     Node widgetNode = (Node) xpath.evaluate(expression,document,XPathConstants.NODE);
     System.out.println(widgetNode.getNodeName());//节点名称
     System.out.println(widgetNode.getNodeValue());//节点值是null，为什么？
     System.out.println(widgetNode.getTextContent());//节点text

  }

}