sql是数据库的结构查询语言，xpath是xml文件的查询语言。

package xpath;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.XPathExpression;import javax.xml.xpath.XPathExpressionException;import javax.xml.xpath.XPathFactory;import org.w3c.dom.Document;import org.w3c.dom.NodeList;import org.xml.sax.SAXException;public class Test {    public static void main(String[] args) throws ParserConfigurationException,            SAXException, IOException, XPathExpressionException {        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();        factory.setNamespaceAware(true); // never forget this!        DocumentBuilder builder;        // 获得document        builder = factory.newDocumentBuilder();        Document doc = builder                .parse("E:\\TEST\\convertTest1\\2016\\201611\\20161107\\book.xml");        // 获得xpath        XPathFactory xpathfactory = XPathFactory.newInstance();        XPath xpath = xpathfactory.newXPath();        // 查询语句        XPathExpression expr = xpath                .compile("//book[author='Neal Stephenson']/title/text()");        // 查询得到结果        Object result = expr.evaluate(doc, XPathConstants.NODESET);        // 遍历查询结果        NodeList nodes = (NodeList) result;        for (int i = 0; i < nodes.getLength(); i++) {            System.out.println(nodes.item(i).getNodeValue());        }    }}

关键在于查询语句