为什么XPath namespace-uri()不能与Java一起开箱即用?

时间:2011-08-21 13:51:26

标签: java xml xpath

我正在尝试使用XPath中的namespace-uri()函数来根据其完全限定名称检索节点。 this online XPath tester中的查询//*[local-name() = 'customerName' and namespace-uri() = 'http://example.com/officeN']等正确返回相关节点。但是,以下自包含Java类不会检索任何内容。我对namespace-uri()做错了什么?

import java.io.StringReader;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
public class Test{
    public static void main(String[] args)throws Exception {

        XPathExpression expr = XPathFactory.newInstance().newXPath().compile(
                "//*[local-name() = 'customerName' and namespace-uri() = 'http://example.com/officeN']");
        String xml=
            "<Agents xmlns:n=\"http://example.com/officeN\">\n"+
            "\t<n:Agent>\n\t\t<n:customerName>Joe Shmo</n:customerName>\n\t</n:Agent>\n"+
            "\t<n:Agent>\n\t\t<n:customerName>Mary Brown</n:customerName>\n\t</n:Agent>\n</Agents>";
        System.out.println(xml);
        Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new InputSource(new StringReader(xml)));
        NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
        System.err.println("\n\nNodes:");
        for (int i = 0; i < nodes.getLength(); i++) {
            System.err.println(nodes.item(i));

        }
    }
}

1 个答案:

答案 0 :(得分:3)

查询看起来很好。您还需要将DocumentBuilderFactory声明为“名称空间感知”。

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
dbf.newDocumentBuilder().parse(new InputSource(new StringReader(xml)));