设计模式（21）模板模式

模式介绍

模板模式定义了操作的轮廓或骨架，由子类定义的具体步骤。

示例

我们以制作面包为例，通常会分为三步：和面、烤、切。

抽象的制作面包方法：

/// <summary>
/// The AbstractClass participant which contains the template method.
/// </summary>
abstract class Bread
{
    public abstract void MixIngredients();

    public abstract void Bake();

    public virtual void Slice() 
    {
        Console.WriteLine("Slicing the " + GetType().Name + " bread!");
    }

    // The template method
    public void Make()
    {
        MixIngredients();
        Bake();
        Slice();
    }
}

具体的多种制作面包方法：

class TwelveGrain : Bread
{
    public override void MixIngredients()
    {
        Console.WriteLine("Gathering Ingredients for 12-Grain Bread.");
    }

    public override void Bake()
    {
        Console.WriteLine("Baking the 12-Grain Bread. (25 minutes)");
    }
}

class Sourdough : Bread
{
    public override void MixIngredients()
    {
        Console.WriteLine("Gathering Ingredients for Sourdough Bread.");
    }

    public override void Bake()
    {
        Console.WriteLine("Baking the Sourdough Bread. (20 minutes)");
    }
}

class WholeWheat : Bread
{
    public override void MixIngredients()
    {
        Console.WriteLine("Gathering Ingredients for Whole Wheat Bread.");
    }

    public override void Bake()
    {
        Console.WriteLine("Baking the Whole Wheat Bread. (15 minutes)");
    }
}

客户端调用：

static void Main(string[] args)
{
    Sourdough sourdough = new Sourdough();
    sourdough.Make();

    TwelveGrain twelveGrain = new TwelveGrain();
    twelveGrain.Make();

    WholeWheat wholeWheat = new WholeWheat();
    wholeWheat.Make();

    Console.ReadKey();
}

总结

模板模式允许对象建立算法的框架，但是将实现细节留给要实现的具体类。

源代码

https://github.com/exceptionnotfound/DesignPatterns/tree/master/TemplateMethod

原文

https://www.exceptionnotfound.net/the-daily-design-pattern-template-method/