How to get attribute value using XPath in Java?

问题:

I have below XML to parse using XPath:

<?xml version="1.0" encoding="UTF-8"?>
<schema>
  <element name="name_ele1" id="name_id_1" >test name1</element>
  <element name="name_ele2" id="name_id_2" >test name2</element>
  <element name="name_ele2" id="name_id_3" >test name3</element>
</schema>

I want to fetch "name" from the xml document based upon the Id I have passed but I am not able to get the required data instead query is returning blank.

XPathExpression expr = xpath.compile("/schema/element[@id='name_id_2']/name/text()");

回答1:

Like this:

XPathExpression expr = xpath.compile("/schema/element[@id='name_id_2']/@name");

Your expression attempts to select the text inside the name element, instead of the value of the name attribute.

回答2:

import java.io.File;
import java.io.FileInputStream;
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.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

public class XMLXpathReadder {

    public static void main(String[] args) throws SAXException, IOException, ParserConfigurationException, XPathExpressionException {



         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document document = db.parse(new FileInputStream(new File("C:\\Test.xml")));// same xml comments as above.

            XPathFactory xpf = XPathFactory.newInstance();
            XPath xpath = xpf.newXPath();
            Element userElement = (Element) xpath.evaluate("/schema/element", document,
                XPathConstants.NODE);
            System.out.println(userElement.getAttribute("id"));
            System.out.println(userElement.getAttribute("name"));

    }

}

Above Code work for me.

But how to read values of all elements. I am getting always first elements node only.

<?xml version="1.0" encoding="UTF-8"?>
<schema>
  <element name="name_ele1" id="_1" >test name1</element>
  <element name="name_ele2" id="_2" >test name2</element>
  <element name="name_ele2" id="_3" >test name3</element>
</schema>