DELPHI中动态调用dll

显式例子:

unit Main;

interface

uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ExtCtrls, Grids, DBGrids, DB, DBTables, DBCtrls;

type

  TForm1 = class(TForm)

    Button1: TButton;

    Edit1: TEdit;

    Edit2: TEdit;

    Image1: TImage;

    DataSource1: TDataSource;

    Table1: TTable;

    Table1SpeciesNo: TFloatField;

    Table1Category: TStringField;

    Table1Common_Name: TStringField;

    Table1SpeciesName: TStringField;

    Table1Lengthcm: TFloatField;

    Table1Length_In: TFloatField;

    Table1Notes: TMemoField;

    Table1Graphic: TGraphicField;

    DBGrid1: TDBGrid;

    procedure Button1Click(Sender: TObject);

  private

    { Private declarations }

  public

    { Public declarations }

  end;

//  function GetInteger(I:Integer): Integer;stdcall;external 'DLLOne.dll';

//  function GetDouble(F:Double): Double;stdcall;external 'DLLOne.dll';

  TGetDouble = function (F:Double): Double; stdcall;

var

  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

var D: Double;

    DLLHandle: THandle;

    Func: TGetDouble;

begin

  Image1.Picture.Assign(Table1Graphic);

  Table1Graphic.Assign(Image1.Picture);

  Exit;

  DLLHandle := LoadLibrary('DLLOne.dll');

  try

  @Func := GetProcAddress(DLLHandle, 'GetDouble');

  //Edit1.Text := IntToStr(GetInteger(2));

  //D := GetDouble(2.2);

  if Assigned(@Func) then

  begin

    D := Func(2.2);

    Edit2.Text := FloatToStr(D);

  end;

  finally

  FreeLibrary(DLLHandle);

  end;

end;

end.

隐式例子:

library DLLOne;

uses

  SysUtils,

  Classes;

{$R *.res}

  function GetDoubleExt(F:Double): Double;stdcall;external 'DLLTwo.dll';

  function GetInt(I:Integer): Integer;stdcall;external 'DLLTwo.dll';

  function GetInteger(I:Integer): Integer;stdcall;

  begin

    Result := GetInt(I);

  end;

  function GetDouble(D:Double): Double;stdcall;

  begin

    Result := GetDoubleExt(D);

  end;

exports

  GetInteger,

  GetDouble;

begin

end.

library DLLTwo;

{ Important note about DLL memory management: ShareMem must be the

  first unit in your library's USES clause AND your project's (select

  Project-View Source) USES clause if your DLL exports any procedures or

  functions that pass strings as parameters or function results. This

  applies to all strings passed to and from your DLL--even those that

  are nested in records and classes. ShareMem is the interface unit to

  the BORLNDMM.DLL shared memory manager, which must be deployed along

  with your DLL. To avoid using BORLNDMM.DLL, pass string information

  using PChar or ShortString parameters. }

uses

  SysUtils,

  Classes;

{$R *.res}

  function GetDoubleExt(D:Double):Double ;stdcall;

  begin

    Result := D;

  end;

  function GetInt(I:Integer): Integer;stdcall;

  begin

    Result := I;

  end;

exports

  GetDoubleExt,

  GetInt;

begin

end.