Delphi 單例模式_Delphi

單例模式簡單示意, delphiXE下測試通過

unit Singleton;(*  單例模式適用於輔助類, 一般伴隨於單元的生命週期*)interfaceuses SysUtils;type  TSingleton = class  public    class function NewInstance : TObject; override;    class function GetInstance : TSingleton;    destructor Destroy; override;    procedure FreeInstance; override;    function Address : integer;  end;implementationvar  FSingleton : TSingleton = nil;  FCanFree : Boolean;{ TSingleton }function TSingleton.Address: integer;begin  Result := Integer(Self);end;destructor TSingleton.Destroy;begin  inherited;end;procedure TSingleton.FreeInstance;begin  if not FCanFree then Exit;  inherited FreeInstance;  FSingleton := nil;end;class function TSingleton.GetInstance: TSingleton;begin  if not Assigned(FSingleton) then  begin    FSingleton := TSingleton.Create;  end;  Result := FSingleton;end;class function TSingleton.NewInstance: TObject;begin  if not Assigned(FSingleton) then  begin    FSingleton := TSingleton(inherited NewInstance);  end;  Result := FSingleton;end;initialization  FSingleton := TSingleton.Create;finalization  FCanFree := True;  if Assigned(FSingleton) then  begin    FSingleton.Free;    FSingleton := nil;  end;end.

unit Unit15;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, Singleton, StdCtrls;type  TForm15 = class(TForm)    btn1: TButton;    procedure btn1Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }  end;var  Form15: TForm15;implementation{$R *.dfm}procedure TForm15.btn1Click(Sender: TObject);var  vTest, vTest2 : TSingleton;begin  vTest := TSingleton.Create;  ShowMessage(IntToStr(vTest.Address));  vTest2 := TSingleton.Create;  ShowMessage(IntToStr(vTest2.Address));//  vTest.free;  FreeAndNil(vTest);  vTest2.free;end;end.