初探Delphi中的插件编程

unit UnitOfficeEntrance;

interface

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

function ShowDLLForm( AHandle : THandle; ACaption : string; AUserID : string )
  : boolean; stdcall;

function FreeDLLForm( AHandle : THandle; ACaption : string; AUserID : string )
  : boolean; stdcall;

implementation

uses UnitOfficialMainForm; // 改成MAINFORM的unit

var
  DLL_Form : TFormOfficialMain; // 改成MAINFORM的NAME

  // -----------------------------------------
  // Name: ShowDLLForm
  // Func: DLL插件调用入口函数
  // Para: AHandle 挂靠程序句柄; ACaption 本窗体标题
  // Rtrn: N/A
  // Auth: CST
  // Date: 2005-6-3
  // -----------------------------------------

function ShowDLLForm( AHandle : THandle; ACaption : string; AUserID : string )
  : boolean;

begin
  result := true;

  try
    Application.Handle := AHandle; // 挂靠到主程序容器
    DLL_Form := TFormOfficialMain.Create( Application ); // 改成MAINFORM的NAME

    try
      with DLL_Form do
      begin
        Caption := ACaption;
        StatusBar.Panels.Items[ 0 ].Text := AUserID;
        // Configure UI
        Show;

      end;

    except
      on e : exception do
      begin
        DLL_Form.Free;

      end;

    end;

  except
    result := false;

  end;

end;

// -----------------------------------------
// Name: FreeDLLForm
// Func: DLL插件调用出口函数
// Para: AHandle 挂靠程序句柄
// Rtrn: true/false
// Auth: CST
// Date: 2005-6-11
// -----------------------------------------

function FreeDLLForm( AHandle : THandle; ACaption : string; AUserID : string )
  : boolean;
begin
  Application.Handle := AHandle; // 挂靠到主程序容器

  if DLL_Form.Showing then
    DLL_Form.Close; // 如果窗口打开先关闭,触发FORM.CLOSEQUERY可取消关闭过程

  if not DLL_Form.Showing then
  begin
    DLL_Form.Free;
    result := true;

  end // 仍然打开状态,说明CLOSEQUERY.CANCLOSE=FALSE

  else
  begin
    result := false;

  end;
end;

end.

library Official;

{ 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,

  UnitOfficialDetailForm in ’ UnitOfficialDetailForm.pas ’,

  UnitOfficialMainForm in ’ UnitOfficialMainForm.pas ’,

  UnitOfficeEntrance in ’ UnitOfficeEntrance.pas ’,

  UnitOfficialClass in ’ .. .. PublicLibraryUnitOfficialClass.pas ’,

  UnitMyDataAdatper in ’ .. .. PublicLibraryUnitMyDataAdatper.pas ’,

  UnitMyHeaders in ’ .. .. PublicLibraryUnitMyHeaders.pas ’;

{$R *.res}

exports ShowDLLForm, FreeDLLForm; // 接口函数

begin

end.

type

//定义接口函数类型,接口函数来自DLL接口

TShowDLLForm = Function(AHandle:THandle; ACaption: String; AUserID:string):Boolean;stdcall;

TFreeDLLForm = Function(AHandle:THandle; ACaption: String; AUserID:string):boolean;stdcall;

var
　ShowDLLForm: TShowDLLForm; //DLL接口函数实例
　FreeDLLForm: TFreeDLLForm;
begin
　try
　begin
　　APlugin.ProcAddr := LoadLibrary(PChar(sPath));
　　APlugin.FuncFreeAddr := GetProcAddress(APlugin.ProcAddr,’FreeDLLForm’);
　　APlugin.FuncAddr := GetProcAddress(APlugin.ProcAddr ,’ShowDLLForm’);

　　@ShowDLLForm:=APlugin.FuncAddr ;
　　@FreeDLLForm:=APlugin.FuncFreeAddr;
　　if ShowDllForm(Self.Handle, APlugin.Caption , APlugin.UserID) then
　　　Result:=True

type

　//定义插件信息类

　TMyPlugins = class
　Caption:String; //DLL窗体标题
　DllFileName:String; //DLL文件路径
　WndClass:String; //窗体标识
　UserID:string; //用户名
　ProcAddr:THandle; //LOADLIBRARY载入的库句柄
　FuncAddr:Pointer; //SHOWDLLFORM函数指针
　FuncFreeAddr:Pointer; //FREEDLLFORM函数指针
end;

//-----------------------------------------

//Name: OpenPlugin

//Func: 插件信息类控制过程： 初始化＝＝》设置权限＝＝》载入DLL窗口

//Para: APlugin-TMyPlugins; sAlias别名; iFuncValue权限值

//Rtrn: N/A

//Auth: CST

//Date: 2005-6-2

//-----------------------------------------

procedure TFormHall.OpenPlugin(AFromActn: TAction ;APlugin:TMyPlugins; sAlias:string; sUserID:string);
　var hWndPlugin:HWnd;
begin
　 
　//判断插件窗口是否已经载入 hWndPlugin:=FindWindow(PChar(APlugin.WndClass),nil);
　if hWndPlugin <> 0 then //插件窗口已经载入
　begin
　　if not IsWindowVisible(hWndPlugin) then
　　begin
　　　AFromActn.Checked := True;
　　　ShowWindow(hWndPlugin,SW_SHOWDEFAULT); //显示
　　end
　　else
　　begin
　　　AFromActn.checked := False;
　　　ShowWindow(hWndPlugin,SW_HIDE) ;
　　end;
　　Exit; //离开创建插件过程
　end;

//初始化插件类实例

if not InitializeMyPlugins(APlugin,sAlias) then
begin
　showmessage(’初始化插件类错误。’);
　exit;
end;

//获得当前权限值

APlugin.UserID := sUserID;
//载入DLL窗口

if not LoadShowPluginForm(APlugin) then
begin
　showmessage(’载入中心插件出错。’);
　exit;
　end;
end;

//-----------------------------------------
//Name: InitializeMyPlugins
//Func: 初始化MYPLUGIN实例 (Caption | DllFileName | IsLoaded)
//Para: APlugin-TMyPlugins
//Rtrn: N/A
//Auth: CST
//Date: 2005-6-2
//-----------------------------------------

function TFormHall.InitializeMyPlugins(APlugin:TMyPlugins; sAlias:String):Boolean;
var
　strSQL:string;
　myDA:TMyDataAdapter;
begin
　Result:=False;
　myDA:=TMyDataAdapter.Create;
　strSQL:=’SELECT * FROM SystemModuleList WHERE modAlias=’+QuotedStr(sAlias);
　try
　　myDA.RetrieveData(strSQL);
　except
　　on E:Exception do
　　begin
　　　result:=false;
　　　myDA.Free ;
　　　exit;
　　end;
　end;
try
　begin
　　with myDA.MyDataSet do
　begin
　　if Not IsEmpty then
　begin
　　APlugin.Caption:= FieldByName(’modName’).Value;
　　APlugin.DllFileName := FieldByName(’modFile’).Value;
　　APlugin.WndClass := FieldByName(’modWndClass’).Value ;
　　result:=True;
　end;
Close;
　end; //end of with...do...
　end; //end of try
　except
　　on E:Exception do
begin
　Result:=False;
　myDA.Free ;
　Exit;
　end; //end of exception
end; //end of try...except

　myDA.Free ; 
end;



//-----------------------------------------

//Name: LoadShowPluginForm

//Func: 载入DLL插件并显示窗口

//Para: APlugin-TMyPlugins

//Rtrn: true-创建成功

//Auth: CST

//Date: 2005-6-2

//-----------------------------------------

function TFormHall.LoadShowPluginForm (const APlugin:TMyPlugins):boolean;

var
　ShowDLLForm: TShowDLLForm; //DLL接口函数实例
　FreeDLLForm: TFreeDLLForm;
　sPath:string; //DLL文件的完整路径
begin
　try
　begin
　　sPath:=ExtractFilepath(Application.ExeName)+ ’plugins’ + APlugin.DllFileName ;
　　APlugin.ProcAddr := LoadLibrary(PChar(sPath));
　　APlugin.FuncFreeAddr := GetProcAddress(APlugin.ProcAddr,’FreeDLLForm’);
　　APlugin.FuncAddr := GetProcAddress(APlugin.ProcAddr ,’ShowDLLForm’);
　　@ShowDLLForm:=APlugin.FuncAddr ;
　　@FreeDLLForm:=APlugin.FuncFreeAddr;
　　if ShowDllForm(Self.Handle, APlugin.Caption , APlugin.UserID) then
　　　Result:=True
　　else
　　　Result:=False;
　　end;
　　except
　　　on E:Exception do
　　begin
　　　Result:=False;
　　　ShowMessage(’载入插件模块错误，请检查PLUGINS目录里的文件是否完整。’);
　　end;
　end;
end; 

procedure TFormHall.ClosePlugin(aPLG:TMyPlugins);
var
　FreeDLLForm:TFreeDLLForm;
begin
　if aPLG.ProcAddr = 0 then exit;
　if aPLG.FuncFreeAddr = nil then exit;
　@FreeDLLForm:=aPLG.FuncFreeAddr;
　if not FreeDLLForm(Application.Handle,’’,’’) then
　　showMessage(’err’);
end;