备忘录模式

实验 20：备忘录模式

本次实验属于模仿型实验，通过本次实验学生将掌握以下内容： 

1、理解备忘录模式的动机，掌握该模式的结构；

2、能够利用备忘录模式解决实际问题。

 

[实验任务一]：多次撤销

 

改进课堂上的“用户信息操作撤销”实例，使得系统可以实现多次撤销（可以使用HashMap、ArrayList等集合数据结构实现）。

类图

 

源代码

import java.util.ArrayList;import java.util.List;
public class Caretaker {
    private List<Memento> list=new ArrayList<>();
    public Memento getMemento() {
        Memento mm=list.get(list.size()-2);
        list.remove(list.size()-2);
        return mm;
    }
    public void setMemento(Memento memento) {
        list.add(memento);
    }
}

public class Memento {
    private String account;
    private String password;
    private String telNo;
    public String getAccount() {
        return account;
    }
    public void setAccount(String account) {
        this.account = account;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getTelNo() {
        return telNo;
    }
    public void setTelNo(String telNo) {
        this.telNo = telNo;
    }
    public Memento(String account, String password, String telNo) {
        this.account = account;
        this.password = password;
        this.telNo = telNo;
    }
    
}
public class UserInfoDTO {
    private String account;
    private String password;
    private String telNo;
    public String getAccount() {
        return account;
    }
    public void setAccount(String account) {
        this.account = account;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getTelNo() {
        return telNo;
    }
    public void setTelNo(String telNo) {
        this.telNo = telNo;
    }
    
    public Memento saveMemento() {
        return new Memento(account,password,telNo);
    }
    public void restoreMemento(Memento memento) {
        this.account=memento.getAccount();
        this.password=memento.getPassword();
        this.telNo=memento.getTelNo();
    }
    public void show() {
        System.out.println("Account:"+this.account);
        System.out.println("Password:"+this.password);
        System.out.println("TelNo:"+this.telNo);
    }
    
}
public class Client {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        UserInfoDTO user=new UserInfoDTO();
        Caretaker c=new Caretaker();
        
        user.setAccount("zhangsan");
        user.setPassword("123456");
        user.setTelNo("1310000000");
        System.out.println("状态一:");
        user.show();
        c.setMemento(user.saveMemento());
        System.out.println("-----------------------------");
        
        user.setPassword("111111");
        user.setTelNo("1310001111");
        System.out.println("状态二:");
        user.show();
        c.setMemento(user.saveMemento());
        System.out.println("-----------------------------");
        
        user.setPassword("zyx666");
        user.setTelNo("15733333333");
        System.out.println("状态三:");
        user.show();
        c.setMemento(user.saveMemento());
        System.out.println("-----------------------------");
        
        user.setPassword("777777");
        user.setTelNo("15511111111");
        System.out.println("状态四:");
        user.show();
        c.setMemento(user.saveMemento());
        System.out.println("-----------------------------");
        
        user.setPassword("666666");
        user.setTelNo("17455555555");
        System.out.println("状态五:");
        user.show();
        c.setMemento(user.saveMemento());
        System.out.println("-----------------------------");
        
        
        user.restoreMemento(c.getMemento());
        System.out.println("回到状态四:");
        user.show();
        System.out.println("-----------------------------");
        
        user.restoreMemento(c.getMemento());
        System.out.println("回到状态三:");
        user.show();
        System.out.println("-----------------------------");
        
        user.restoreMemento(c.getMemento());
        System.out.println("回到状态二:");
        user.show();
        System.out.println("-----------------------------");
        
        user.restoreMemento(c.getMemento());
        System.out.println("回到状态一:");
        user.show();
        System.out.println("-----------------------------");
    }

}