备忘录模式(Memento)

情节：如果再给我一次机会。。。

定义：在不破坏封闭的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可将该对象恢复到原先保存的状态。

结构图：

public class GameRole {public int vit;public int atk;public int defense;public int getVit() {return vit;}public void setVit(int vit) {this.vit = vit;}public int getAtk() {return atk;}public void setAtk(int atk) {this.atk = atk;}public int getDefense() {return defense;}public void setDefense(int defense) {this.defense = defense;}public void StateDisplay(){System.out.println("VIT"+this.vit);System.out.println("ATK"+this.atk);System.out.println("DEFENSE"+this.defense);}public void GetInitState(){this.atk = 100;this.defense = 100;this.vit = 100;}public void Fight(){this.atk = 0;this.defense = 0;this.vit = 0;}//保存角色状态public Memento SaveState(){return new Memento(vit, atk, defense);}//恢复角色状态public void RecoveryState(Memento memento){this.atk = memento.atk;this.defense = memento.defense;this.vit = memento.vit;}}public class Memento {//体力，攻击力，防御力public int vit;public int atk;public int defense;public Memento(int vit, int atk, int defense) {super();this.vit = vit;this.atk = atk;this.defense = defense;}public int getVit() {return vit;}public void setVit(int vit) {this.vit = vit;}public int getAtk() {return atk;}public void setAtk(int atk) {this.atk = atk;}public int getDefense() {return defense;}public void setDefense(int defense) {this.defense = defense;}}public class Caretaker {private Memento memento;public Memento getMemento() {return memento;}public void setMemento(Memento memento) {this.memento = memento;}}public class Client {public static void main(String[] args) {//大战前GameRole xiaoRole = new GameRole();xiaoRole.GetInitState();xiaoRole.StateDisplay();//保存进度Caretaker stateAdmin = new Caretaker();stateAdmin.setMemento(xiaoRole.SaveState());//大战时xiaoRole.Fight();xiaoRole.StateDisplay();//恢复之前状态xiaoRole.RecoveryState(stateAdmin.getMemento());xiaoRole.StateDisplay();}}

        把要保存的细节封装在Memento中，哪一天要更改保存的细节就不用影响客户端了

        比较适用于功能比较复杂的，但需要维护或记录属性历史的类;需要保存的属性只是众多属性的一小部分时，Originator可以根据保存的Memento信息还原到前一状态。