1>新建Dll文件TestLib.dll
新建Unit文件U_TestFunc
U_TestFunc代码如下：
unit U_TestFunc;
interface
uses //尽可能的少uses这样会缩小dll的体积
SysUtils;
//求和
function Sum(x1,x2: Integer): Integer; stdcall
implementation
function Sum(x1,x2: Integer): Integer; stdcall
begin
Result := x1+x2;
end;
end.
TestLib代码如下：
library TestLib;
uses SysUtils,
U_TestFunc in ‘U_TestFunc.pas‘;
{$R *.res}
exports
Sum;
begin
end.
2>调用方法 源码如下：
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, Buttons;
type
TForm1 = class(TForm)
Edit1: TEdit;
BitBtn1: TBitBtn;
Edit2: TEdit;
BitBtn2: TBitBtn;
procedure BitBtn1Click(Sender: TObject);
procedure BitBtn2Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
function Sum(a1,a2: Integer): Integer; stdcall; external ‘C:\TestLib.dll‘;
procedure TForm1.BitBtn1Click(Sender: TObject);
begin
//if FileExists(‘C:\TestLib.dll‘) then 这里感觉这两个函数没有什么区别，文件在本地不在本地貌似效果都一样。
if LocaleFileExists(‘C:\TestLib.dll‘) then
Edit1.Text := IntToStr(Sum(100,200))
else
ShowMessage(‘文件不存在！‘);
end;
procedure TForm1.BitBtn2Click(Sender: TObject);
type
TIntFunc = function(a1,a2: Integer): Integer; stdcall;
var
Th: THandle;
Tf: TIntFunc;
begin
Th := LoadLibrary(‘C:\TestLib.dll‘);
if Th>0 then
begin
try
@Tf := GetProcAddress(Th, PAnsiChar(‘Sum‘));
if @Tf<>nil then
begin
Edit2.Text := IntToStr(Tf(100,200));
end else
ShowMessage(‘Sum函数没有找到！‘);
finally
FreeLibrary(Th); //释放Dll
end;
end else
ShowMessage(‘TestLib.dll文件没有找到！‘);
end;
end.
原文：http://www.cnblogs.com/vin2008/p/3979504.html