Delphi封装类到DLL

unit ITest;

interface

type
  IT = interface
    function GetString:string;
    procedure ShowMsg(p:PChar);
    procedure Msg;
  end;

implementation

end.

unit UTest;

interface

uses
  SysUtils,
  Windows,
  ITest;

type
  TTest = class(TInterfacedObject,IT)
  private
    i:Integer;
  protected

  public
    constructor Create; //override;
    destructor Destroy; override;
    function GetString:string;
    procedure ShowMsg(p:PChar);
    procedure Msg;
  published

  end;

implementation

constructor TTest.Create;
begin
  i:=0;
end;

destructor TTest.Destroy;
begin
  inherited;
end;

function TTest.GetString:string;
begin
  Result := ‘Test string‘;
end;

procedure TTest.ShowMsg(p:PChar);
begin
  MessageBox(0,p,‘Test‘,MB_OK);
end;

procedure TTest.Msg;
begin
  Inc(i);
  MessageBox(0,‘Test MessageBox‘,PChar(IntToStr(i)),MB_OK);
end;

end.

library Test;

uses
  SysUtils,
  Classes,
  ITest in ‘ITest.pas‘,
  UTest in ‘UTest.pas‘;

{$R *.res}

function TestCreate:IT; stdcall;
begin
  Result := TTest.Create;
end;

exports
  TestCreate; //用此初始化

begin
end.

uses
  ITest;  //引用单元

function TestCreate:IT; stdcall; external ‘Test.dll‘ name ‘TestCreate‘; //引用DLL函数

//声明作为测试
  private
    AA:IT;
    BB:IT;

procedure TForm1.FormCreate(Sender: TObject);
begin
  AA:= TestCreate;
  BB:= TestCreate;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Button1.Caption := AA.GetString;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  AA.ShowMsg(‘123abc‘);
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  AA.Msg;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
  BB.Msg;
end;