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") @Override public Iterator getPrefixes(String namespaceURI) { throw new UnsupportedOperationException(); } @Override public String getPrefix(String namespaceURI) { throw new UnsupportedOperationException(); } @Override public 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。