[javaEE] 三层架构案例-用户模块（一）详解编程语言

package com.tsh.dao; 
 
import java.util.List; 
 
import org.dom4j.Document; 
import org.dom4j.DocumentHelper; 
import org.dom4j.Element; 
 
import com.tsh.domain.User; 
import com.tsh.util.XmlDaoUtil; 
 
public class XmlUserDao { 
    /** 
     * 根据用户名查找user 
     * @param username 
     * @return 
     */ 
    public User findUserByUsername(String username){ 
        Document dom=XmlDaoUtil.getDom(); 
        Element root=dom.getRootElement(); 
        //使用XPATH语法 
        List<Element> list=root.selectNodes("//user[@username='"+username+"']"); 
        if(list.size()>0){ 
            Element userElement=list.get(0); 
            String uname=userElement.attributeValue("username"); 
            String password=userElement.attributeValue("password"); 
            //将用户信息封装到bean 
            User user=new User(); 
            user.setUsername(uname); 
            user.setPassword(password); 
            user.setPassword_confirm(password); 
            return user; 
        } 
        return null; 
    } 
    /** 
     * 添加用户 
     * @param user 
     */ 
    public void addUser(User user){ 
        Document dom=XmlDaoUtil.getDom(); 
        Element root=dom.getRootElement(); 
        //创建<user>元素 
        Element userElement=DocumentHelper.createElement("user"); 
        userElement.setAttributeValue("username", user.getUsername()); 
        userElement.setAttributeValue("password", user.getPassword()); 
        //挂载到<users> 
        root.add(userElement); 
        //回写到xml文件 
         
    } 
}

package com.tsh.util; 
 
import java.net.URL; 
 
import org.dom4j.Document; 
import org.dom4j.io.SAXReader; 
 
public class XmlDaoUtil { 
    private static URL path=XmlDaoUtil.class.getClassLoader().getResource("user.xml"); 
    /** 
     * 使用静态代码块，对象只实例化一次 
     */ 
    private static Document dom; 
    static{ 
        SAXReader reader=new SAXReader(); 
        try { 
            //类加载器找到物理路径 
            dom=reader.read(path); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
    /** 
     * 获取xml 
     * @return 
     */ 
    public static Document getDom(){ 
        return dom; 
    } 
    /** 
     * 写入xml 
     */ 
    public static void writeXml(){ 
         
    } 
}

package com.tsh.domain; 
 
import java.io.Serializable; 
 
public class User implements Serializable{ 
    private String username; 
    private String password; 
    private String password_confirm; 
    public String getUsername() { 
        return username; 
    } 
    public void setUsername(String username) { 
        this.username = username; 
    } 
    public String getPassword() { 
        return password; 
    } 
    public void setPassword(String password) { 
        this.password = password; 
    } 
    public String getPassword_confirm() { 
        return password_confirm; 
    } 
    public void setPassword_confirm(String password_confirm) { 
        this.password_confirm = password_confirm; 
    } 
     
}

<?xml version="1.0" encoding="UTF-8"?> 
<users> 
<user username="admin" password="admin"></user> 
</users>