xpath

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