Delphi设计模式-Abstract Factory

模式的描述可以参考[1]，下面举一个Delphi中的例子。

通常Delphi中的Form都是自动Create，也可以在Form中写代码来创建（通常是在主Form中）。下面以Abstract Factory来创建Form。

//unit AbstractF

TAbstractFactory = class

public

function CreateForm : TForm;virtual;abstract;

end;

//unit ConcreteFA

TConcreteFactoryA = class(TAbstractFactory)

public

function CreateForm : TForm; override;

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

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls, AbstractF;

type

TfrmMain = class(TForm)

btnConcreteA: TButton;

btnContreteB: TButton;

procedure btnConcreteAClick(Sender: TObject);

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.

[参考资料]

1.《设计模式-可复用面向对象软件的基础》