裝飾者模式

OO原則：

對擴展開放，對修改關閉

 

OO模式：

裝飾者模式(Decorate)，動態的將責任附加到對象上。想要擴展功能，裝飾著模式提供有別于繼承的另一種選擇

 

類結構圖：

 

星巴茲咖啡

1.Beverage飲料虛基類

/// <summary>/// Beverage 飲料虛基類/// </summary>public abstract class Beverage{    protected string description = "Unknown Beverage";    //對飲料描述    public string GetDescription()    {        return description;    }    //返回原料價格    public abstract double Cost();}

 

2.Espresso濃縮咖啡

/// <summary>/// Espresso 濃縮咖啡/// </summary>public class Espresso : Beverage{    //構造函數public Espresso(){        description = "Espresso";}    //價格    public override double Cost()    {        return 1.99;    }}

3.HouseBlend綜合咖啡

/// <summary>/// HouseBlend 綜合咖啡/// </summary>public class HouseBlend : Beverage{    //構造函數public HouseBlend(){        description = "House Blend Coffee";}    //價格    public override double Cost()    {        return 0.89;    }}

4.CondimentDecorator調料基類

/// <summary>/// CondimentDecorator 調料基類/// </summary>public abstract class CondimentDecorator : Beverage{    //public abstract string GetDescription();}

5.Milk咖啡裝飾者：牛奶

/// <summary>/// Milk 咖啡裝飾者：牛奶/// </summary>public class Milk : CondimentDecorator{    Beverage beverage;    //構造函數，傳入一個Beverage對象用於包裝    public Milk(Beverage beverage){        this.beverage = beverage;        this.description = beverage.GetDescription() + ", Milk";}    //價格    public override double Cost()    {        return 0.1 + beverage.Cost();    }}

6.Mocha咖啡裝飾者：摩卡

/// <summary>/// Mocha 咖啡裝飾者：摩卡/// </summary>public class Mocha : CondimentDecorator{    Beverage beverage;    //構造函數，傳入一個Beverage對象用於包裝public Mocha(Beverage beverage){        this.beverage = beverage;        this.description = beverage.GetDescription() + ", Mocha";}    //價格    public override double Cost()    {        return 0.2 + beverage.Cost();    }}

6.調用

//濃縮咖啡protected void Button1_Click(object sender, EventArgs e){    Beverage beverage = new Espresso();    beverage = new Mocha(beverage);    beverage = new Milk(beverage);    Response.Write(beverage.GetDescription() + "  $" + beverage.Cost());}//綜合咖啡protected void Button2_Click(object sender, EventArgs e){    Beverage beverage = new HouseBlend();    beverage = new Mocha(beverage);    Response.Write(beverage.GetDescription() + " $" + beverage.Cost());}