文章目录
- 实现
- 举例
- 应用
- 钩子 Hook
模板方法模式是一种基于继承的设计模式,由两部分构成:
- 抽象父类(一般封装了子类的算法框架)
- 具体的实现子类
实现
简单地通过继承就可以实现
举例
足球赛 和 篮球赛 都有 3 个步骤,初始化,开始游戏,结束游戏
我们发现他们都有这个过程,就可以把相同的点提取出来,设置成一个模板!
这里我们举例的 3 个方法都是抽象方法,有时如果子类的行为是一致的,可以直接实现具体方法~
using System;public abstract class Game
{public void Play(){Initialize();StartGame();EndGame();}protected abstract void Initialize();protected abstract void StartGame();protected abstract void EndGame();
}public class FootballGame : Game
{protected override void Initialize(){Console.WriteLine("Football game initialized. Setting up teams and players.");}protected override void StartGame(){Console.WriteLine("Football game started. Kickoff!");}protected override void EndGame(){Console.WriteLine("Football game ended. Final score and statistics displayed.");}
}public class BasketballGame : Game
{protected override void Initialize(){Console.WriteLine("Basketball game initialized. Setting up teams and players.");}protected override void StartGame(){Console.WriteLine("Basketball game started. Tip-off!");}protected override void EndGame(){Console.WriteLine("Basketball game ended. Final score and statistics displayed.");}
}public class Program
{public static void Main(string[] args){Game footballGame = new FootballGame();footballGame.Play();Console.WriteLine();Game basketballGame = new BasketballGame();basketballGame.Play();}
}
应用
常被架构师用来搭建项目的框架,程序员负责往里面填空
比如 Java 程序员经常用 HttpServlet 来开发项目,他包含 7 个生命周期,每个生命周期都对应一个 do 方法,这些方法就需要 HttpServlet 的子类进行 具体实现
钩子 Hook
根据上面的例子,如果有一种非常特别的球赛不需要 Initialize 就可以开始呢?
我们可以在容易变化的方法处设置一个 Hook,他可以有一个默认的实现,需不需要 Hook 挂钩则由子类自行决定,这样程序就有了变化的可能~
using System;public abstract class Game
{public void Play(){Initialize();StartGame();EndGame();}protected virtual void Initialize(){Console.WriteLine("Game initialized. Setting up teams and players.");// 在这里添加挂钩(Hook)行为AdditionalInitialization();}protected abstract void StartGame();protected abstract void EndGame();protected virtual void AdditionalInitialization(){// 默认的挂钩行为为空}
}public class FootballGame : Game
{protected override void StartGame(){Console.WriteLine("Football game started. Kickoff!");}protected override void EndGame(){Console.WriteLine("Football game ended. Final score and statistics displayed.");}protected override void AdditionalInitialization(){Console.WriteLine("Additional initialization for Football game.");}
}public class BasketballGame : Game
{protected override void StartGame(){Console.WriteLine("Basketball game started. Tip-off!");}protected override void EndGame(){Console.WriteLine("Basketball game ended. Final score and statistics displayed.");}protected override void AdditionalInitialization(){Console.WriteLine("Additional initialization for Basketball game.");}
}public class Program
{public static void Main(string[] args){Game footballGame = new FootballGame();footballGame.Play();Console.WriteLine();Game basketballGame = new BasketballGame();basketballGame.Play();}
}