XML操作举例→实现用户登录

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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();
    }

}
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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="aa@sina.com" 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", " ");
}
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();
}

}


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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();
    }

}
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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);

}


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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);

}
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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);
}
}

}


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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);
        }
    }
    
}
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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("aa@sina.com");
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");

}
}


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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("aa@sina.com");
        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");

    }
}
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原文地址：https://www.cnblogs.com/lingyi1111/p/4467005.html