用DLL实现插件的简单演示

这是DLL的代码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}beginend.

这是调用窗体的代码本例只使用了一个DLL，所以当有多个DLL时，需要循环DLL所在目录，依次加载DLLunit Main;interfaceuses 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ShowInfoend;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.