XPath实例

<?xml version="1.0" encoding="UTF-8"?>
<inventory>
    <book year="2000">
        <title>Snow Crash</title>
        <author>Neal Stephenson</author>
        <publisher>Spectra</publisher>
        <isbn>0553380958</isbn>
        <price>14.95</price>
    </book>
    <book year="2005">
        <title>Burning Tower</title>
        <author>Larry Niven</author>
        <author>Jerry Pournelle</author>
        <publisher>Pocket</publisher>
        <isbn>0743416910</isbn>
        <price>5.99</price>
    </book>
    <book year="1995">
        <title>Zodiac</title>
        <author>Neal Stephenson</author>
        <publisher>Spectra</publisher>
        <isbn>0553573862</isbn>
        <price>7.50</price>
    </book>
</inventory>

public class XPathTest {
    @Test
    public void test() throws Exception {
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        builderFactory.setValidating(true);
        builderFactory.setNamespaceAware(false);
        builderFactory.setIgnoringComments(true);
        builderFactory.setIgnoringElementContentWhitespace(false);
        builderFactory.setCoalescing(false);
        builderFactory.setExpandEntityReferences(true);

        DocumentBuilder builder = builderFactory.newDocumentBuilder();
        builder.setErrorHandler(new ErrorHandler() {
            @Override
            public void warning(SAXParseException exception) throws SAXException {
                System.out.println("warning+"+exception.getMessage());
            }

            @Override
            public void error(SAXParseException exception) throws SAXException {
                System.out.println("error+"+exception.getMessage());
            }

            @Override
            public void fatalError(SAXParseException exception) throws SAXException {
                System.out.println("fatalError+"+exception.getMessage());
            }
        });

        Document document = builder.parse("cn.test.inventory.xml");
        XPathFactory factory = XPathFactory.newInstance();
        XPath xPath = factory.newXPath();
        XPathExpression expression = xPath.compile("//book[author='Neal Stephenson']/title/text()");
        Object res = expression.evaluate(document, XPathConstants.NODESET);
        System.out.println("查询作者为 Neal Stephenson 的图书的标题: ");
        NodeList nodes = (NodeList) res;
        for (int i = 0; i < nodes.getLength(); i++) {
            System.out.println(nodes.item(i).getNodeValue());
        }

        System.out.println("查询 1997 年之后的图书的标题:");
        nodes = (NodeList) xPath.evaluate("//book[@year>1997]/title/text()",document,XPathConstants.NODESET);
        for (int i = 0; i < nodes.getLength(); i++) {
            System.out.println(nodes.item(i).getNodeValue());
        }

        System.out.println("查询 1997 年之后的图书的属性和标题:");
        nodes = (NodeList) xPath.evaluate("//book[@year>1997]/@*|//book[@year>1997]/title/text()",document,XPathConstants.NODESET);
        for (int i = 0; i < nodes.getLength(); i++) {
            System.out.println(nodes.item(i).getNodeValue());
        }
    }
}