【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