如何使用Xpath Java从xml中获取元素

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathConstants;

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse("path/to/xml/file.xml");

XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();

XPathExpression expr = xpath.compile("//elementName");

Object result = expr.evaluate(document, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;

for (int i = 0; i < nodes.getLength(); i++) {
    Node node = nodes.item(i);
    if (node.getNodeType() == Node.ELEMENT_NODE) {
        Element element = (Element) node;
        // 处理元素
    }
}