Delphi 接口托管实现

 unit Unit1;

 interface

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

 type
   TForm1 = class(TForm)
     Button1: TButton;
     procedure Button1Click(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;

   IMyInterface = interface(IUnknown)
    procedure ShowString(s: string);
   end;

   TMyClass = class(TInterfacedObject, IMyInterface)
   public
     procedure ShowString(s: string);
   end;

   TSecondClass = class(TInterfacedObject, IMyInterface)
   protected
     myInterface: IMyInterface;
   protected
     property my: IMyInterface read myInterface implements IMyInterface;
   public
     constructor Create(AOwner: TObject); overload;
   end;

 var
   Form1: TForm1;

 implementation

 {$R *.dfm}

 procedure TForm1.Button1Click(Sender: TObject);
 var
   myclass: TMyClass;
   mySecondclass: TSecondClass;
 begin
   myclass := TMyClass.Create;
   mySecondclass := TSecondClass.Create(nil);
   myclass.ShowString('sss');
   mySecondclass.my.ShowString('aaa');
   myclass.Free;
   mySecondclass.Free;
 end;

 { TMyClass }

 procedure TMyClass.ShowString(s: string);
 begin
   ShowMessage(s);
 end;

 { TSecondClass }

 constructor TSecondClass.Create(AOwner: TObject);
 begin
   myInterface := TMyClass.Create;
 end;

 end.