场景:
录入大批人员资料,正在录入当前人资料时,发现上一个人录错了,此时需要回复上一个人的资料,在进行修改。
word文档编辑时,忽然电脑死机或者断电,在打开时,可以看到word提示你恢复到以前的文档
核心:
就是保存某个对象内部状态的拷贝,这样以后就可以将该对象恢复到原先状态
使用场景:
1.棋类游戏中的悔棋
2.普通软件中的撤销操作
3.数据库软件中的,事务管理中的回滚操作
4.ps中的历史记录
实现:
package com.gcxzflgl.memento; /** * 备忘录类 * @author Administrator * */ public class EmpMemento { private String ename; private int age; private double salary; public EmpMemento(Emp e) { this.ename = e.getEname(); this.age = e.getAge(); this.salary = e.getSalary(); } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } }
package com.gcxzflgl.memento; /** * 源发器类 * @author Administrator * */ public class Emp { private String ename; private int age; private double salary; //进行备忘操作,并返回备忘录对象 public EmpMemento memento(){ return new EmpMemento(this); } //进行数据恢复,恢复成制定备忘录对象的值 public void recovery(EmpMemento mmt){ this.ename = mmt.getEname(); this.age = mmt.getAge(); this.salary = mmt.getSalary(); } public Emp(String ename, int age, double salary) { super(); this.ename = ename; this.age = age; this.salary = salary; } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public double getSalary() { return salary; } public void setSalary(double salary) { this.salary = salary; } }
package com.gcxzflgl.memento; /** * 负责人类 * 负责管理备忘录对象 * @author Administrator * */ public class CareTaker { private EmpMemento memento; // private List<EmpMemento> list = new ArrayList<EmpMemento>(); public EmpMemento getMemento() { return memento; } public void setMemento(EmpMemento memento) { this.memento = memento; } }
package com.gcxzflgl.memento; public class Client { public static void main(String[] args) { CareTaker taker = new CareTaker(); Emp emp = new Emp("高晨曦", 18, 900); System.out.println("第一次打印对象:"+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary()); taker.setMemento(emp.memento()); //备忘一次 emp.setAge(38); emp.setEname("晨曦"); emp.setSalary(9000); System.out.println("第二次打印对象:"+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary()); emp.recovery(taker.getMemento()); //恢复到备忘录对象保存的状态 System.out.println("第三次打印对象:"+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary()); } }