Delphi設計模式-Abstract Factory (轉)

Delphi設計模式-Abstract Factory (轉)[@more@]

  的描述可以參考[1]，下面舉一箇中的例子。

  通常Delphi中的Form都是自動Create，也可以在Form中寫程式碼來建立（通常是在主Form中）。下面以Abstract Factory來建立Form。

//unit AbstractF

  TAbstractFactory = class
  public
  function CreateFo: TForm;virtual;abstract;
  end;

//unit ConcreteFA

  TConcreteFactoryA = class(TAbstractFactory)
  public
  function CreateForm : TForm; overr;
  end;

{ TConcreteFactoryB }

function TConcreteFactoryA.CreateForm: TForm;
begin
  Result := TfrmFormA.Create(Application);
  Result.ShowModal;
end;

//unit ConcreteFB

  TConcreteFactoryB = class(TAbstractFactory)
  public
  function CreateForm : TForm; override;
  end;

{ TConcreteFactoryB }

function TConcreteFactoryB.CreateForm: TForm;
begin
  Result := TfrmFormB.Create(Application);
  Result.ShowModal;
end;

//主Form

unit MainFrm;

interface

uses
  , Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, AbstractF;

type
  TfrmMain = class(TForm)
  btnConcreteA: TButton;
  btnContreteB: TButton;
  procedure btnConcreteAClick(Sender: T);
  procedure btnContreteBClick(Sender: TObject);
  private
  { Private declarations }
  FAbstractFactory: TAbstractFactory;
  public
  { Public declarations }
  end;

var
  frmMain: TfrmMain;

implementation

uses ConcreteFA, ConcreteFB;

{$R *.dfm}

procedure TfrmMain.btnConcreteAClick(Sender: TObject);
begin
  FAbstractFactory:= TConcreteFactoryA.Create;
  FAbstractFactory.CreateForm;
  FAbstractFactory.Free;
end;

procedure TfrmMain.btnContreteBClick(Sender: TObject);
begin
  FAbstractFactory:= TConcreteFactoryB.Create;
  FAbstractFactory.CreateForm;
  FAbstractFactory.Free;
end;

end.

[參考資料]

1.《設計模式-可複用面向的基礎》