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>