xpath dom 解析

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder builder = factory.newDocumentBuilder();
         FileInputStream file = new FileInputStream(legoInstalledFile);
         Document doc = builder.parse(file);
        
        
         XPathFactory xPathFactory = XPathFactory.newInstance();
         XPath xpath = xPathFactory.newXPath();
         XPathExpression expr = xpath.compile("//install/installpath");
         Object result = expr.evaluate(doc, XPathConstants.NODESET);
        
         NodeList nodes = (NodeList) result;
       NamedNodeMap attributes = nodes.item(0).getAttributes();
       return attributes.item(0).getTextContent();