import org.dom4j.*;
import org.dom4j.io.SAXReader;

import java.util.List;

public class XmlDemo {

    public static void main(String[] args) throws Exception {
        SAXReader reader = new SAXReader();
        Document doc = reader.read("demo.xml");

        // device[@user_agent]
        // 查找有user_agent属性的device节点
        XPath xpathSelector = DocumentHelper.createXPath("//device[@user_agent]");
        List nodes = xpathSelector.selectNodes(doc);

        for (Object obj : nodes) {
            Element n = (Element) obj;
            System.out.println(n.attribute("user_agent").getText());
        }
    }
}