XPath提取xml文档数据

package itcast.dom4j;

import java.io.File;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;

public class Demo1 {

    /**
     * @param args
     * @throws Exception 
     */
    public static void main(String[] args) throws Exception {

        String username = "11";
        String password = "123";

        // 检测xml文档是否有匹配的用户名和密码
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File("src/users.xml"));
        
        Node node = document.selectSingleNode("//user[@username='"+username+"'and @password='"+password+"']");
        
        if(node==null){
            System.out.println("用户名或密码错误");
        }else{
            System.out.println("login success");
        }
    }

}

<?xml version="1.0" encoding="UTF-8"?>
<users>
    <user id="1" username="aaa" password="123" email="aa@sina.com" />
    <user id="2" username="bbb" password="123" email="aa@sina.com" />
</users>