模式简析

/*** */
/*** 备忘录模式* 动机：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。* 解决的问题：所谓备忘录模式就是在不破坏封装的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态，* 这样可以在以后将对象恢复到原先保存的状态。* 优点： 1、给用户提供了一种可以恢复状态的机制，可以使用户能够比较方便地回到某个历史的状态。* 2、实现了信息的封装，使得用户不需要关心状态的保存细节。* 缺点：消耗资源。如果类的成员变量过多，势必会占用比较大的资源，而且每一次保存都会消耗一定的内存。* 使用场景： * 1、需要保存/恢复数据的相关状态场景。 * 2、提供一个可回滚的操作。* 注意： 1、为了符合迪米特原则，还要增加一个管理备忘录的类。 2、为了节约内存，可使用原型模式+备忘录模式。 * * * * * @author **/

具体实例

/*** 游戏进度保存* 失败后可以从保存的位置继续游戏**/
public class Demo1 {public static void main(String[] args) {GameRole g1 = new GameRole();g1.GetInitState();GameRole g2 = new GameRole();g2.setVitality(g1.getVitality());g2.setAttack(g1.getAttack());g2.setDefense(g1.getDefense());g1.DisplayState();g1.Fight();g1.DisplayState();System.out.println("回复保存时的状态");g1.setVitality(g2.getVitality());g1.setAttack(g2.getAttack());g1.setDefense(g2.getDefense());g1.DisplayState();}
}
class GameRole{private int vitality;private int attack;private int defense;public int getVitality() {return vitality;}public void setVitality(int vitality) {this.vitality = vitality;}public int getAttack() {return attack;}public void setAttack(int attack) {this.attack = attack;}public int getDefense() {return defense;}public void setDefense(int defense) {this.defense = defense;}public void DisplayState() {System.out.println("游戏角色当前状态：\n");System.out.println("生命力："+vitality+"\n");System.out.println("攻击力："+attack+"\n");System.out.println("防御力："+defense+"\n");}public void GetInitState() {this.vitality=100;this.attack=100;this.defense=100;}public void Fight() {this.vitality=0;this.attack=0;this.defense=0;}
}
/** 存在的问题* 将所有细节都暴露给了客户端，客户端承担了太多责任* 代码是紧耦合在一起*/

/** 备忘录模式基本代码*/
public class Demo2 {public static void main(String[] args) {Originator o = new Originator();o.setState("状态1");o.showState();Caretaker c =new Caretaker();c.setMemento(o.createMemento());o.setState("状态2");o.showState();o.setMemenot(c.getMemento());o.showState();}
}
//备忘录
class Memento{private String state;public Memento(String state) {this.state = state;}public String getState() {return state;}public void setState(String state) {this.state = state;}}
//创建者
class Originator{private String state;public String getState() {return state;}public void setState(String state) {this.state = state;}public Memento createMemento(){return new Memento(this.state);}public void setMemenot(Memento memento) {state = memento.getState();}public void showState() {System.out.println("当前状态:"+state);}
}
class Caretaker{private Memento memento;public Memento getMemento() {return memento;}public void setMemento(Memento memento) {this.memento = memento;}}

/*** 游戏进度保存----备忘录模式实现* 失败后可以从保存的位置继续游戏**/
public class Demo1 {public static void main(String[] args) {GameRole g1 = new GameRole();g1.GetInitState();g1.DisplayState();RoleCaretaker rc =new RoleCaretaker();rc.setRm(g1.SaveState());g1.Fight();g1.DisplayState();g1.RecoverState(rc.getRm());g1.DisplayState();}
}
class GameRole{private int vitality;private int attack;private int defense;public int getVitality() {return vitality;}public void setVitality(int vitality) {this.vitality = vitality;}public int getAttack() {return attack;}public void setAttack(int attack) {this.attack = attack;}public int getDefense() {return defense;}public void setDefense(int defense) {this.defense = defense;}public void DisplayState() {System.out.println("游戏角色当前状态：\n");System.out.println("生命力："+vitality+"\n");System.out.println("攻击力："+attack+"\n");System.out.println("防御力："+defense+"\n");}public void GetInitState() {this.vitality=100;this.attack=100;this.defense=100;}public void Fight() {this.vitality=0;this.attack=0;this.defense=0;}public RoleMemento SaveState() {return new RoleMemento(vitality, attack, defense);}public void RecoverState(RoleMemento rm) {this.vitality=rm.getVitality();this.attack=rm.getAttack();this.defense=rm.getDefense();}
}
class RoleMemento{private int vitality;private int attack;private int defense;public RoleMemento(int vitality, int attack, int defense) {super();this.vitality = vitality;this.attack = attack;this.defense = defense;}public int getVitality() {return vitality;}public void setVitality(int vitality) {this.vitality = vitality;}public int getAttack() {return attack;}public void setAttack(int attack) {this.attack = attack;}public int getDefense() {return defense;}public void setDefense(int defense) {this.defense = defense;}}class RoleCaretaker{private RoleMemento rm;public RoleMemento getRm() {return rm;}public void setRm(RoleMemento rm) {this.rm = rm;}
}