java常用设计模式之备忘录模式------------------------------ 备忘录模式(Memento) --------------------
java常用设计模式之备忘录模式
------------------------------ 备忘录模式(Memento) -------------------------------
(1)
备忘录模式属于行为型模式，其意图是在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这
个状态，这样以后就可以将对象恢复到原先保存的状态。(2)
实例如下:
有一个对象Employee.除了属性外,还需要一个保存,还原状态的方法.
有一个对象Memento,用来记录Employee每一个时刻的状态,
CareTaker,用来保存,拿回Memento.需要一个保存,还原状态的方法.->需要一个指针,一个容器.package memento;
public class Memento{
??? String name;
??? int age;
??? public Memento(String name,int age){
?????? this.name = name;
?????? this.age = age;
??? }
}
Employee模式：
package memento;
public class Employee{
??? private String name;
??? private int age;
??? public Employee(String aName,int aAge){
?????? name = aName;
?????? age = aAge;
??? }
??? public void setName(String aName){
?????? name = aName;
??? }
??? public void setAge(int aAge){
?????? age = aAge;
??? }
??? public Memento? saveMemento(){
?????? return new Memento(name,age);
??? }
??? public void restoreMemento(Memento memento){
?????? age = memento.age;
?????? name = memento.name;
??? }
??? public int getAge(){
?????? return age;
??? }
??? public String getName(){
?????? return name;
??? }
}
CareTaker代码：
package memento;
import java.util.Vector;
public class CareTaker{
??? private Vector v;
??? private int? current;
??? public CareTaker(){
?????? current = -1;
?????? v = new Vector();
??? }
??? public void setMemento(Memento mem){
?????? current ++;
?????? v.add(mem);
??? }
??? public Memento getMemento(){
?????? if(current>0){
?????????? current --;
?????????? return(Memento) v.get(current);
?????? }
?????? return null;
??? }
}
Client代码：
package memento;
public class Client{
??? public static void show(Employee e){
?????? System.out.println("-----------------------------------");
?????? System.out.println("Name:"+e.getName());
?????? System.out.println("Age:" + e.getAge());
?????? System.out.println("-----------------------------------");
??? }
??? public static void main(String[] args){
?????? Employee e = new Employee("lili",25);
?????? CareTaker ct = new CareTaker();
?????? show(e);
?????? ct.setMemento(e.saveMemento());
?????? e.setName("litianli");
?????? show(e);
?????? ct.setMemento(e.saveMemento());
?????? e.setAge(45);
?????? show(e);
?????? ct.setMemento(e.saveMemento());
?????? //restore
?????? e.restoreMemento(ct.getMemento());
?????? show(e);
?????? e.restoreMemento(ct.getMemento());
?????? show(e);
??? }
}转自：http://shenzhenchufa.blog.51cto.com/730213/161581
