Delphi 设计模式：《HeadFirst设计模式》Delphi7代码---装饰模式之StarBuzzCoffee[转] - 小光zfg

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{《HeadFirst设计模式》之装饰模式 }
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{ 本单元中的类为被装饰者 }
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{ 编译工具: Delphi7.0 }
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{ E-Mail : guzh-0417@163.com }
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unit uComponent;
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interface
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type
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TBeverage = class(TObject) //抽象饮料类
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protected
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FDescription: String;
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public
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function GetDescription: String; virtual;
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function Cost: Double; virtual; abstract;
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end;
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TEspresso = class(TBeverage) //浓咖啡饮料类
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public
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constructor Create;
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function Cost: Double; override;
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end;
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THouseBlend = class(TBeverage) //具体HouseBlend饮料类
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public
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constructor Create;
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function Cost: Double; override;
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end;
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TDarkRoast = class(TBeverage) //具体DarkRoast饮料类
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public
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constructor Create;
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function Cost: Double; override;
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end;
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implementation
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{ TBeverage }
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function TBeverage.GetDescription: String;
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begin
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Result := FDescription;
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end;
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{ TEspresso }
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function TEspresso.Cost: Double;
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begin
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Result := 1.99;
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end;
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constructor TEspresso.Create;
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begin
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FDescription := 'Espresso';
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end;
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{ THouseBlend }
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function THouseBlend.Cost: Double;
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begin
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Result := 0.89;
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end;
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constructor THouseBlend.Create;
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begin
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FDescription := 'House Blend Coffee';
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end;
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{ TDarkRoast }
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function TDarkRoast.Cost: Double;
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begin
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Result := 0.99;
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end;
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constructor TDarkRoast.Create;
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begin
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FDescription := 'Dark Roast Coffee';
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end;
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end.

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{《HeadFirst设计模式》之装饰模式 }
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{ 装饰者既继承又组合被装饰者。继承 }
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{ 在这里的意图主要是类型匹配 —— }
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{ 与被装饰者是同一类型。 }
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{ 编译工具: Delphi7.0 }
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{ E-Mail : guzh-0417@163.com }
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unit uDecorator;
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interface
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uses
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uComponent;
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type
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TCondimentDecorator = class(TBeverage) //抽象装饰者
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end;
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TMocha = class(TCondimentDecorator) //具体装饰者：Mocha
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private
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FBeverage: TBeverage;
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public
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constructor Create(aBeverage: TBeverage);
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function GetDescription: String; override;
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function Cost: Double; override;
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end;
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TSoy = class(TCondimentDecorator) //具体装饰者：Soy
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private
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FBeverage: TBeverage;
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public
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constructor Create(aBeverage: TBeverage);
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function GetDescription: String; override;
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function Cost: Double; override;
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end;
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TWhip = class(TCondimentDecorator) //具体装饰者：Whip
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private
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FBeverage: TBeverage;
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public
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constructor Create(aBeverage: TBeverage);
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function GetDescription: String; override;
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function Cost: Double; override;
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end;
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implementation
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{ TMocha }
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function TMocha.Cost: Double;
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begin
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Result := FBeverage.Cost + 0.20;
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end;
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constructor TMocha.Create(aBeverage: TBeverage);
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begin
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FBeverage := aBeverage;
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end;
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function TMocha.GetDescription: String;
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begin
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Result := FBeverage.GetDescription + ', Mocha';
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end;
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{ TSoy }
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function TSoy.Cost: Double;
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begin
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Result := FBeverage.Cost + 0.15;
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end;
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constructor TSoy.Create(aBeverage: TBeverage);
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begin
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FBeverage := aBeverage;
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end;
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function TSoy.GetDescription: String;
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begin
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Result := FBeverage.GetDescription + ', Soy';
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end;
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{ TWhip }
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function TWhip.Cost: Double;
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begin
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Result := FBeverage.Cost + 0.10;
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end;
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constructor TWhip.Create(aBeverage: TBeverage);
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begin
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FBeverage := aBeverage;
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end;
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function TWhip.GetDescription: String;
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begin
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Result := FBeverage.GetDescription + ', Whip';
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end;
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end.

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{《HeadFirst设计模式》之装饰模式 }
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{ 客户端 }
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{ 编译工具: Delphi7.0 }
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{ E-Mail : guzh-0417@163.com }
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program pStarBuzzCoffee;
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{$APPTYPE CONSOLE}
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uses
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SysUtils,
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uComponent in 'uComponent.pas',
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uDecorator in 'uDecorator.pas';
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var
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aBeverage1: TBeverage;
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aBeverage2: TBeverage;
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aBeverage3: TBeverage;
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begin
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aBeverage1 := TEspresso.Create;
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Writeln(aBeverage1.GetDescription + ' $' + FloatToStr(aBeverage1.Cost));
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FreeAndNil(aBeverage1);
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aBeverage2 := TDarkRoast.Create;
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aBeverage2 := TWhip.Create(TMocha.Create(TMocha.Create(aBeverage2)));
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Writeln(aBeverage2.GetDescription + ' $' + FloatToStr(aBeverage2.Cost));
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FreeAndNil(aBeverage2);
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aBeverage3 := THouseBlend.Create;
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aBeverage3 := TSoy.Create(aBeverage3);
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aBeverage3 := TMocha.Create(aBeverage3);
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aBeverage3 := TWhip.Create(aBeverage3);
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Writeln(aBeverage3.GetDescription + ' $' + FloatToStr(aBeverage3.Cost));
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FreeAndNil(aBeverage3);
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Readln;
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end.