第十六篇:备忘录模式

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说在开头:其实我个人并不认为这是什么设计模式...因为完全没有什么价值嘛，不过既然多本书上对其有介绍，那我还是写一下吧！

备忘录模式是用来实现备份，还原的一种代码组织结构；什么时候需要备份还原呢？非常常见的是游戏中的保存进度，打BOSS前需要先将当前进度保存一下，等到一不小心挂了，还可以马上恢复到打BOSS前...不然得江湖再见一切重头开始，那该多蛋疼？？？

那好，我们就以游戏为例写一段代码吧！

//游戏角色class Role{//攻击点数private int attackCount;//防御点数private int defenceForcesCount;//经验数private int experieceCount;//精力//该数是不需要存档的...private int vigorCount;public int getAttackCount() {return attackCount;}public void setAttackCount(int attackCount) {this.attackCount = attackCount;}public int getDefenceForcesCount() {return defenceForcesCount;}public void setDefenceForcesCount(int defenceForcesCount) {this.defenceForcesCount = defenceForcesCount;}public int getExperieceCount() {return experieceCount;}public void setExperieceCount(int experieceCount) {this.experieceCount = experieceCount;}public int getVigorCount() {return vigorCount;}public void setVigorCount(int vigorCount) {this.vigorCount = vigorCount;}@Overridepublic String toString() {return "Role [attackCount=" + attackCount + ", defenceForcesCount="+ defenceForcesCount + ", experieceCount=" + experieceCount+ ", vigorCount=" + vigorCount + "]";}}

//备份数据管理者接口，也就是存档位置，//我们在单机游戏中不是可以看到多个存档点么,我们可以自由选择存档点嘛！interface Director{//备份void preserve(Role role );//读取存档点还原Role rollBack();}//存档位置1class DirectorOne implements Director{private Role role;@Overridepublic void preserve(Role role) {this.role = role;}@Overridepublic Role rollBack() {return this.role;}}

//备份帮助者对象，这里注意一下，其实我们可以直接对Role对象进行克隆，完全复制一份进行保存而不要这个对象，//之所以一个个属性去get and set，是因为可能有某些值是不需要备份的，比如精力class BackHelper{/*** * 进行备份的地方 * @param role 要备份的角色 * @param director 要备份到那个存档点 */public void preserve( Role role,Director director){Role newRole = new Role();newRole.setAttackCount(role.getAttackCount());newRole.setDefenceForcesCount(role.getDefenceForcesCount());newRole.setExperieceCount(role.getExperieceCount());director.preserve(newRole);}}

最后来测试一下：

public class Test {public static void main(String[] args) {Role role = new Role();role.setAttackCount(10);role.setDefenceForcesCount(88);role.setExperieceCount(100);role.setVigorCount(72);System.out.println(role);//备份一下，保存到存档点Director director = new DirectorOne();BackHelper backHelper = new BackHelper();backHelper.preserve(role, director);//戴上了某件超强装备，改变攻击力role.setAttackCount(10000);System.out.println(role);//打BOSS死了，重新读档role = director.rollBack();System.out.println(role);}}

输出******************************************************************

Role [attackCount=10, defenceForcesCount=88, experieceCount=100, vigorCount=72]
Role [attackCount=10000, defenceForcesCount=88, experieceCount=100, vigorCount=72]
Role [attackCount=10, defenceForcesCount=88, experieceCount=100, vigorCount=0]

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Ok，就写这么多吧，实在没什么好些的...

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