Delphi 用DLL实现插件的简单实例

library MyDll;  uses  SysUtils,  Dialogs,  Classes;  procedure ShowInfo(info:PChar);stdcall; begin  ShowMessage('您选择了【'+info+'】'); end;  function GetCaption:Pchar; begin  Result := '中国'; end;  exports ShowInfo,         GetCaption;  {$R *.res}  begin end. 

unit Main;  interface  uses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, Menus, ExtCtrls;  type  TShowInfo = procedure (info:PChar);stdcall;  TGetCaption = function : PChar;stdcall;    TForm1 = class(TForm)   Button1: TButton;   Button2: TButton;   MainMenu1: TMainMenu;   Image1: TImage;   procedure Button2Click(Sender: TObject); private   { Private declarations }   FHandel : THandle;   //DLL句柄   FProAddress: Pointer; //DLL中ShowInfo的地址   showinfo: TShowInfo;  //为动态加载DLL而设   procedure LoadPlusIn; //加载插件（DLL）   procedure ItemClick(Sender: TObject);  //自定义菜单点击事件  public   { Public declarations }  end;  var  Form1: TForm1;  implementation  {$R *.dfm}  procedure TForm1.Button2Click(Sender: TObject); begin  LoadPlusIn; end;  procedure TForm1.ItemClick(Sender: TObject); begin  @showinfo := FProAddress;   //取地址  if @showinfo <> nil then   showinfo(PWideChar(TMenuItem(Sender).Caption)); //执行DLL中的ShowInfo end;  procedure TForm1.LoadPlusIn; var  getcaption: TGetCaption;  item : TMenuItem; begin  FHandel := LoadLibrary('MyDll.dll');  //加载  if FHandel = 0 then  begin   ShowMessage('加载失败！');   Exit;  end  else  begin   @getcaption := GetProcAddress(FHandel,'GetCaption');  //取DLL中GetCaption地址   if @getcaption <> nil then   begin    item := TMenuItem.Create(MainMenu1);  //创建一个菜单    item.Caption := getcaption;       //取Caption，即调用DLL中的GetCaption    FProAddress := GetProcAddress(FHandel,'ShowInfo'); //取得DLL中ShowInfo的地址    item.OnClick := ItemClick;       //赋予菜单项的点击事件    MainMenu1.Items.Add(item);       //添加到主菜单   end;   end; end;  end.