清单 4. 用固定的 XPath 表达式查询 XML 文档的完整程序

 
 

  
  
importjava.io.IOException;
  
  
importorg.w3c.dom.*;
  
  
importorg.xml.sax.SAXException;
  
  
importjavax.xml.parsers.*;
  
  
importjavax.xml.xpath.*;
  
  
publicclassXPathExample{
  
  
publicstaticvoidmain(String[]args)
  
  
throwsParserConfigurationException,SAXException,
  
  
IOException,XPathExpressionException{
  
  
DocumentBuilderFactorydomFactory=DocumentBuilderFactory.newInstance();
  
  
domFactory.setNamespaceAware(true);//neverforgetthis!
  
  
DocumentBuilderbuilder=domFactory.newDocumentBuilder();
  
  
Documentdoc=builder.parse("books.xml");
  
  
XPathFactoryfactory=XPathFactory.newInstance();
  
  
XPathxpath=factory.newXPath();
  
  
XPathExpressionexpr
  
  
=xpath.compile("//book[author='NealStephenson']/title/text()");
  
  
Objectresult=expr.evaluate(doc,XPathConstants.NODESET);
  
  
NodeListnodes=(NodeList)result;
  
  
for(inti=0;i<nodes.getLength();i++){
  
  
System.out.println(nodes.item(i).getNodeValue());
  
  
}
  
  
}
  
  
}