当老胡还是小胡的时候,跟随团队一起开发一款游戏。这款游戏是一款末日生存类游戏,玩家可以
项目开发的很顺利,我那时得到一个任务,是为游戏做一个新手教程,在这个教程里面,通过一系列步骤,引导新手玩家熟悉这个游戏。游戏设计给出的教程包含以下步骤
同时要求在不用的阶段显示不同的提示以正确引导玩家。考虑合成装备算是高级玩家才会接触到的功能,所以暂时不打算放在新手教程里面。
当老大把任务交给我的时候,我感觉简单爆了,不就写一个新手教程么,要求又那么明确,应该要不了多少时间。于是,一个上午过后,我交出了如下代码。
首先用一个枚举,表示教程进行的不同程度
enum TutorialState { GetGold, GetIron, KillEnemy, LevelUp }
无需多言,封装收集到的资源数、击杀敌人数量、角色等级和一些升级接口等
class Player { private int ironNum; private int goldNum; private int enemyKilled; private int level; public int IronNum => ironNum; public int GoldNum => goldNum; public int EnemyKilled => enemyKilled; public int Level => level; public void CollectIron(int num) { ironNum += num; } public void CollectGold(int num) { goldNum += num; } public void KillEnemy() { enemyKilled++; } public void LevelUp() { level++; } }
定义一个教程类,包括
class GameTutorial { private TutorialState currentState; private Player player; public GameTutorial(Player player) { this.player = player; } public void ShowHelpDescription() { switch (currentState) { case TutorialState.GetGold: Console.WriteLine("Please follow instruction to get gold"); break; case TutorialState.GetIron: Console.WriteLine("Please follow instruction to get Iron"); break; case TutorialState.KillEnemy: Console.WriteLine("Please follow instruction to kill enemy"); break; case TutorialState.LevelUp: Console.WriteLine("Please follow instruction to Up your level"); break; default: throw new Exception("Not Support"); } } public void ValidateState() { switch (currentState) { case TutorialState.GetGold: { if (player.GoldNum > 0) { Console.WriteLine("Congratulations, you finished Gold Collect Phase"); currentState = TutorialState.GetIron; } else { Console.WriteLine("You need to collect gold"); } break; } case TutorialState.GetIron: { if (player.IronNum > 0) { Console.WriteLine("Congratulations, you finished Iron Collect Phase"); currentState = TutorialState.KillEnemy; } else { Console.WriteLine("You need to collect Iron"); } break; } case TutorialState.KillEnemy: { if (player.EnemyKilled > 0) { Console.WriteLine("Congratulations, you finished Enemy Kill Phase"); currentState = TutorialState.LevelUp; } else { Console.WriteLine("You need to kill enemy"); } break; } case TutorialState.LevelUp: { if (player.Level > 0) { Console.WriteLine("Congratulations, you finished the whole tutorial"); currentState = TutorialState.LevelUp; } else { Console.WriteLine("You need to level up"); } break; } default: throw new Exception("Not Support"); } } }
static void Main(string[] args) { Player player = new Player(); GameTutorial tutorial = new GameTutorial(player); tutorial.ShowHelpDescription(); tutorial.ValidateState(); //收集黄金 player.CollectGold(1); tutorial.ValidateState(); tutorial.ShowHelpDescription(); //收集木头 player.CollectIron(1); tutorial.ValidateState(); tutorial.ShowHelpDescription(); //杀敌 player.KillEnemy(); tutorial.ValidateState(); tutorial.ShowHelpDescription(); //升级 player.LevelUp(); tutorial.ValidateState(); }
运行结果
看起来一切都好。。编写的代码既能够根据当前步骤显示不同的提示,还可以成功的根据玩家的进度切换到下一个步骤。
于是,我自信满满的申请了code review,按照我的想法,这段代码通过code review应该是板上钉钉的事情,谁知,老大看到代码,差点没背过气去。。。稍微平复了一下心情之后,他给了我几个灵魂拷问。
本来以为如此简单的一个功能,没想到还是有那么多弯弯道道,只怪自己还是太年轻啊!最后他悠悠的告诉我,去看看状态模式吧,想想这段代码可以怎么重构。
对象拥有内在状态,当内在状态改变时允许其改变行为,这个对象看起来像改变了其类
有点意思,看来我们可以把教程的不同步骤抽象成不同的状态,然后在各个状态内部实现切换状态和显示帮助文档的逻辑,这样做的好处是
接着我们看看UML,
一目了然,在我们的例子里面,state就是教程子步骤,context就是教程类,内部包含教程子步骤并转发请求给教程子步骤,我们跟着来重构一下代码吧。
第一步我们需要删除之前的枚举,取而代之的是一个抽象类当作状态基类,即,各个教程步骤类的基类。注意,每个子状态要自己负责状态切换,所以我们需要教程类暴露接口以满足这个功能。
abstract class TutorialState { public abstract void ShowHelpDescription(); public abstract void Validate(GameTutorial tutorial); }
重构教程类体现在以下方面
class GameTutorial { private TutorialState currentState; private Player player; public int PlayerIronNum => player.IronNum; public int PlayerLevel => player.Level; public int PlayerGoldNum => player.GoldNum; public int PlayerEnemyKilled => player.EnemyKilled; public void SetState(TutorialState state) { currentState = state; } public GameTutorial(Player player) { this.player = player; currentState = TutorialStateContext.GetGold; } public void ShowHelpDescription() { currentState.ShowHelpDescription(); } public void ValidateState() { currentState.Validate(this); } }
接着我们创建各个子状态代表不同的教程步骤
class TutorialSateGetGold : TutorialState { public override void ShowHelpDescription() { Console.WriteLine("Please follow instruction to get gold"); } public override void Validate(GameTutorial tutorial) { if (tutorial.PlayerGoldNum > 0) { Console.WriteLine("Congratulations, you finished Gold Collect Phase"); tutorial.SetState(TutorialStateContext.GetIron); } else { Console.WriteLine("You need to collect gold"); } } } class TutorialStateGetIron : TutorialState { public override void ShowHelpDescription() { Console.WriteLine("Please follow instruction to get Iron"); } public override void Validate(GameTutorial tutorial) { if (tutorial.PlayerIronNum > 0) { Console.WriteLine("Congratulations, you finished Iron Collect Phase"); tutorial.SetState(TutorialStateContext.KillEnemy); } else { Console.WriteLine("You need to collect iron"); } } } class TutorialStateKillEnemy : TutorialState { public override void ShowHelpDescription() { Console.WriteLine("Please follow instruction to kill enemy"); } public override void Validate(GameTutorial tutorial) { if (tutorial.PlayerEnemyKilled > 0) { Console.WriteLine("Congratulations, you finished enemy kill Phase"); tutorial.SetState(TutorialStateContext.LevelUp); } else { Console.WriteLine("You need to collect kill enemy"); } } } class TutorialStateLevelUp : TutorialState { public override void ShowHelpDescription() { Console.WriteLine("Please follow instruction to level up"); } public override void Validate(GameTutorial tutorial) { if (tutorial.PlayerLevel > 0) { Console.WriteLine("Congratulations, you finished the whole tutorial"); } } }
这是模式中没有提到的知识点,一般来说,为了避免大量的子状态对象被创建,我们会构造一个状态容器,以静态变量的方式初始化需要使用的子状态。
static class TutorialStateContext { public static TutorialState GetGold; public static TutorialState GetIron; public static TutorialState KillEnemy; public static TutorialState LevelUp; static TutorialStateContext() { GetGold = new TutorialSateGetGold(); GetIron = new TutorialStateGetIron(); KillEnemy = new TutorialStateKillEnemy(); LevelUp = new TutorialStateLevelUp(); } }
测试代码部分保持不变,直接运行,结果和原来一样,重构成功。