XML操作举例→实现用户登录

XmlUtils.java 

package cn.zyw.utils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

//3
public class XmlUtils {
    private static String filepath;
    static{
        filepath=XmlUtils.class.getClassLoader().getResource("users.xml").getPath();
        filepath=filepath.replace("%20"," ");
    }
    public static Document getDocument() throws Exception{
        SAXReader reader = new SAXReader();
        Document document = reader.read(new File(filepath));
        return document;
    }
    public static void write2Xml(Document document) throws Exception{
        OutputFormat format = OutputFormat.createPrettyPrint();
        format.setEncoding("UTF-8");
        XMLWriter writer = new XMLWriter(new FileOutputStream(filepath),format );
        writer.write( document );
        writer.close();
    }

}

有时我们想做做一个小的项目需要保存一定的数据，如果用数据库当然是可以的。但是总觉得有点浪费资源。所以今天就学习了一点Xml总结如下：

1：Xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<users>
    <user id="234343434" username="aaa" password="123" email="[e-mail]" birthday="1900-09-18" nickname="强子" />
</users>

2:操作Xml文件的工具类

XmlUtils.java 

package cn.zyw.utils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

//3
public class XmlUtils {
    private static String filepath;
    static{
        filepath=XmlUtils.class.getClassLoader().getResource("users.xml").getPath();
        filepath=filepath.replace("%20",format );
        writer.write( document );
        writer.close();
    }

}

3:用户登录的Dao

UserDao .java 
package cn.zyw.dao;
import cn.zyw.domain.User;
//5
public interface UserDao {
 void add(User user);
 User find(String username,String password);
 //查找注册的用户是否在数据库中存在
 boolean find(String username);
}
4:用户登录的实现类

UserDaoImpl .java 
package cn.zyw.dao.impl;
import java.text.SimpleDateFormat;
import org.dom4j.Document;
import org.dom4j.Element;
import cn.zyw.dao.UserDao;
import cn.zyw.domain.User;
import cn.zyw.utils.XmlUtils;
//2
public class UserDaoImpl implements UserDao {
 public void add(User user){
 try {
 Document document=XmlUtils.getDocument();
 Element root=document.getRootElement();//得到根节点
 Element user_tag=root.addElement("user");
 user_tag.setAttributeValue("id",user.getId());
 user_tag.setAttributeValue("username",user.getUsername());
 user_tag.setAttributeValue("password",user.getPassword());
 user_tag.setAttributeValue("email",user.getEmail());
 user_tag.setAttributeValue("nickname",user.getNickname());
 user_tag.setAttributeValue("birthday",user.getBirthday()==null ? "" : user.getBirthday().toLocaleString());
 XmlUtils.write2Xml(document);
 } catch (Exception e) {
 throw new RuntimeException(e);
 }
 }
 public User find(String username,String password){
 try {
 Document document=XmlUtils.getDocument();
 Element e=(Element) document.selectSingleNode("//user[@username='"+username+"' and @password='"+password+"']");
 if(e==null)
 return null;
 User user=new User();
 user.setUsername(e.attributeValue("username"));//获取xml里面的值
 user.setNickname(e.attributeValue("nickname"));
 user.setPassword(e.attributeValue("password"));
 user.setEmail(e.attributeValue("email"));
 user.setId(e.attributeValue("id"));
 String date=e.attributeValue("birthday");
 if(date==null || date.equals("")){
 user.setBirthday(null); 
 }else{
 SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
 user.setBirthday(df.parse(date));
 }
 return user; 
 } catch (Exception e) {
 throw new RuntimeException(e);
 }
 }
 //查找注册的用户是否在数据库中存在
 public boolean find(String username){ 
 try {
 Document document=XmlUtils.getDocument();
 Element e=(Element) document.selectSingleNode("//user[@username='"+username+"']");
 if(e==null){
 return false;
 }
 
 return true; 
 } catch (Exception e) {
 throw new RuntimeException(e);
 }
 }
 
}
5:用户登录的测试

UserDaoTest.java 
package junit.test;
import java.util.Date;
import org.junit.Test;
import cn.zyw.dao.UserDao;
import cn.zyw.dao.impl.UserDaoImpl;
import cn.zyw.domain.User;
//4
public class UserDaoTest {
 @Test
 public void testAdd(){
 User user=new User();
 user.setBirthday(new Date());
 user.setEmail("[e-mail]");
 user.setId("34343434");
 user.setNickname("李子");
 user.setPassword("123");
 user.setUsername("aaa"); 
 
 UserDao dao=new UserDaoImpl();
 dao.add(user);
 }
 @Test
 public void testFind(){
 UserDao dao=new UserDaoImpl();
 User user=dao.find("aaa","123");
 String aa=user.getEmail();
 if(aa.endsWith("kk"))
 {
 System.out.println("kkdf");
 }
 }
 @Test
 public void testFindByUsername(){
 UserDao dao=new UserDaoImpl();
 boolean b=dao.find("aaa");
 }
}