学步园

 //================  dll   工程文件 ======

library d;

uses
  SysUtils,
  Classes,
  ActiveX,
  OleDB, ADOInt,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

  exports showForm,showForm2;

begin
end.

//============  dll 里的窗体代码 ========

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, Grids, DBGrids, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    DBGrid1: TDBGrid;
    ADOConnection1: TADOConnection;
    ADOQuery1: TADOQuery;
    DataSource1: TDataSource;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  procedure showForm(adoC:TAdoConnection;H:Thandle);stdcall;
  function  showForm2:TFormClass; stdcall;
implementation

{$R *.dfm}

  procedure showForm(adoC:TAdoConnection;H:Thandle);
  var
     form1:Tform1;
     p:^TAdoconnection;
  begin
     application.Handle := h;

     form1 := TForm1.Create(nil);
     p := @(form1.ADOConnection1);
     p^ := adoc;
     form1.ADOQuery1.Connection := p^;    // 这里只能这样，不能在设计时指定
    // showmessage(p^.ConnectionString);
     form1.ShowModal;
     form1.Close;

  end;

  function showForm2:TFormClass;
  begin
    result := TForm1;
  end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  with self.ADOQuery1 do
  begin

     sql.Clear;
     sql.Add('select * from dt_dept ');
     open;
  end;
end;

end.

// ==================  主程序代码 ==================

unit Unit2;

interface

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

type
  TForm2 = class(TForm)
    ADOConnection1: TADOConnection;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    form1 :tform;
  public
    { Public declarations }
  end;

  procedure showForm(adoC:TAdoConnection;H:Thandle);stdcall;external 'd.dll';
  function showForm2:TFormClass;stdcall;external 'd.dll';
var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
var
  p:pointer;
begin
  p := @ADOConnection1;
  showForm(ADOConnection1,self.Handle);
end;

procedure TForm2.Button2Click(Sender: TObject);
var
  tform1:TFormClass;

begin
  tform1 := showForm2;
  form1 := tform1.Create(nil) ;
  form1.Show;

end;

procedure TForm2.Button3Click(Sender: TObject);
begin
  form1.Close;
end;

end.