delphi dll

 

动态链接库（Dynamic Link Library）

• 不是可执行的二进制文件
• 包含一个可以由多个程序同时使用的代码和数据的库
• 一般位于windows/system32下

调用dll的方式

1. 外部声明
2. 动态加载

创建dll

library TestDll;

uses
  SysUtils,
  Classes;

{$R *.res}

function min(num1,num2 : Integer) : Integer;stdcall;
begin
  if num1 < num2 then
    Result := num1
  else
    Result := num2;
end;

exports
  min;

begin
end.

 

调用dll

 

1. 外部声明（静态调用）

   unit Unit1;
   
   interface
   
   uses
     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
     Dialogs, StdCtrls;
   
     function min(num1,num2 : Integer) : Integer;stdcall; external 'TestDll.dll' name 'min';
   type
     TForm1 = class(TForm)
       edt1: TEdit;
       edt2: TEdit;
       btn1: TButton;
       procedure btn1Click(Sender: TObject);
     private
   
     public
       { Public declarations }
     end;
   
   var
     Form1: TForm1;
   
   implementation
   
   {$R *.dfm}
   
   procedure TForm1.btn1Click(Sender: TObject);
   var
     N1,N2 : Integer;
   begin
     N1 := StrToInt(edt1.Text);
     N2 := StrToInt(edt2.Text);
     ShowMessage( IntToStr( min(N1,N2) ) );
   end;
   
   end.

    
2. 动态加载

   unit Unit1;
   
   interface
   
   uses
     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
     Dialogs, StdCtrls;
   
   type
     TForm1 = class(TForm)
       edt1: TEdit;
       edt2: TEdit;
       btn1: TButton;
       procedure btn1Click(Sender: TObject);
     private
   
     public
       { Public declarations }
     end;
   
     TMin = function (num1,num2 : Integer): Integer; stdcall;
   
   var
     Form1: TForm1;
   
   implementation
   
   {$R *.dfm}
   
   procedure TForm1.btn1Click(Sender: TObject);
   var
     OneHandle : THandle; //定义一个句柄变量
     min : TMin;
   begin
     OneHandle := LoadLibrary('TestDll.dll');
     try
       if OneHandle <> 0 then //如果载入成功则获取ShowCalendar函数的地址
         @min := GetProcAddress(OneHandle, 'min');
         if not (@min = nil) then
         //如果找到该函数则在主窗体的Label1中显示DLL窗体中设定的日期
           ShowMessage( IntToStr(min(StrToInt(edt1.Text),StrToInt(edt2.Text))));
     finally
       FreeLibrary(OneHandle); //调用完毕收回DLL占用的资源
     end;
   end;
   
   end.