【GOF23设计模式】备忘录模式

来源：http://www.bjsxt.com/ 
一、【GOF23设计模式】_备忘录模式、多点备忘、事务操作、回滚数据底层架构

package com.test.memento;
/**
 * 源发器类
 */
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.test.memento;
/**
 * 备忘录类
 */
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.test.memento;

import java.util.ArrayList;

/**
 * 负责人类
 */
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.test.memento;

public class Client {
    public static void main(String[] args) {
        CareTaker careTaker = new CareTaker();

        Emp emp = new Emp("小高", 18, 900);
        System.out.println("第一次打印对象："+emp.getEname()+"--"
                +emp.getAge()+"--"+emp.getSalary());

        careTaker.setMemento(emp.memento());//备忘一次

        emp.setAge(38);
        emp.setEname("小搞");
        emp.setSalary(9000);

        System.out.println("第二次打印对象："+emp.getEname()+"--"
                +emp.getAge()+"--"+emp.getSalary());

        emp.recovery(careTaker.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());
    }
}

控制台输出：
第一次打印对象：小高--18--900.0
第二次打印对象：小搞--38--9000.0
第三次打印对象：小高--18--900.0