利用xpath获取节点值实例
这几天做xml打包、解包的通用工具，学习了下xpath的使用方法，它可以很方便查询某一节点的值，有点类似于jquery的选择器，具体事例如下：
public String queryNodeValue(final Document doc, String expression)throws XPathExpressionException {XPathFactory factory = XPathFactory.newInstance();XPath xpath = factory.newXPath();xpath.setNamespaceContext(new NamespaceContext() {@SuppressWarnings("rawtypes")@Overridepublic Iterator getPrefixes(String namespaceURI) {throw new UnsupportedOperationException();}@Overridepublic String getPrefix(String namespaceURI) {throw new UnsupportedOperationException();}@Overridepublic String getNamespaceURI(String prefix) {return doc.lookupNamespaceURI(prefix);}});XPathExpression expr = xpath.compile(expression);Object result = expr.evaluate(doc, XPathConstants.STRING);return result == null ? null : result.toString();}??上面是获取document的元素值的通用方法。