udataaccesshelper.pas

抽象三层访问数据库示例

unit uDataAccessHelper;

interface

uses
  Windows, Classes, SysUtils, Forms, uADODataAccess, uDOADataAccess,
  uWebDataAccess, uIDataAccess, uDataAccess;

type
  TDataAccessHelper = class
  public
    class function GetADODataAccess: IDataAccess;
    class function GetDOADataAccess: IDataAccess;
    class function GetWebDataAccess: IDataAccess;
    class function GetADODataAccessInstance(AOwner: TComponent): TDataAccess;
    class function GetDOADataAccessInstance(AOwner: TComponent): TDataAccess;
    class function GetWebDataAccessInstance(AOwner: TComponent): TDataAccess;
  end;

implementation

{ TDataAccessHelper }

class function TDataAccessHelper.GetADODataAccess: IDataAccess;
begin
  Result := GetADODataAccessInstance(nil);
end;

class function TDataAccessHelper.GetADODataAccessInstance(
  AOwner: TComponent): TDataAccess;
begin
  result := TADODataAccess.Create(AOwner);
end;

class function TDataAccessHelper.GetDOADataAccess: IDataAccess;
begin
  Result := GetDOADataAccessInstance(nil);
end;

class function TDataAccessHelper.GetDOADataAccessInstance(
  AOwner: TComponent): TDataAccess;
begin
  Result := TDOADataAccess.Create(AOwner);
end;

class function TDataAccessHelper.GetWebDataAccess: IDataAccess;
begin
  Result := GetWebDataAccessInstance(nil);
end;

class function TDataAccessHelper.GetWebDataAccessInstance(
  AOwner: TComponent): TDataAccess;
begin
  Result := TWebDataAccess.Create(AOwner);
end;

end.