Java编程练习：使用分层结构，基于XML文件，实现模拟用户登录

有如下XML文件 user.xml，里面存放的是用户登录信息。

<?xml version="1.0" encoding="UTF-8"?>
<root>
<user id="u01" username="well" password="1234"/>
<user id="u02" username="lily" password="4321"/>
</root>

分层设计思想如下：

表现层：LoginUI::input():User LoginUI::output():String

业务层：LoginBusiness::check(User):boolean

根据上面的要求，写出程序：

（1）编写User类

package web.java.xml.exercise1;

public class User {
private String id;
private String username;
private String password;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
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;
}

}

（2）编写表现层LoginUI类，用于在控制台接收用户输入，并封装为javaBean

package web.java.xml.exercise1;

import java.util.Scanner;

public class LoginUI {
public User input(){
User user = new User();
Scanner scanner = new Scanner(System.in);

System.out.print("username:");
String username = scanner.nextLine();
System.out.print("password:");
String password = scanner.nextLine();
user.setUsername(username);
user.setPassword(password);

return user;
}
public void output(boolean flag){
if(flag){
System.out.println("Login success!");
} else {
System.out.println("Login failed!");
}
}
}

（3）编写业务层LoginBusiness类，实现用户登录

package web.java.xml.exercise1;

import java.io.File;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class LoginBusiness {
public static void main(String[] args) throws Exception {
LoginUI loginUI = new LoginUI();
LoginBusiness loginBusiness = new LoginBusiness();

User user = loginUI.input();
boolean flag = loginBusiness.check(user);
loginUI.output(flag);
}

public boolean check(User user) throws Exception {
boolean flag = false;
SAXReader saxReader = new SAXReader();
File file = new File("src/web/java/xml/exercise1/users.xml");
Document doc = saxReader.read(file);
String xpath = "//user[@username='"+user.getUsername()+"' and @password='"+user.getPassword()+"']";
Element ele = (Element) doc.selectSingleNode(xpath);
if(ele!=null){
flag = true;
}
return flag;
}
}