//--------------------------------------------------------------------------- #include //--------------------------------------------------------------------------- // Important note about DLL memory management when your DLL uses the // static version of the RunTime Library: // // If your DLL exports any functions that pass String objects (or structs/ // classes containing nested Strings) as parameter or function results, // you will need to add the library MEMMGR.LIB to both the DLL project and // any other projects that use the DLL. You will also need to use MEMMGR.LIB // if any other projects which use the DLL will be performing new or delete // operations on any non-TObject-derived classes which are exported from the // DLL. Adding MEMMGR.LIB to your project will change the DLL and its calling // EXE's to use the BORLNDMM.DLL as their memory manager. In these cases, // the file BORLNDMM.DLL should be deployed along with your DLL. // // To avoid using BORLNDMM.DLL, pass string information using "char *" or // ShortString parameters. // // If your DLL uses the dynamic version of the RTL, you do not need to // explicitly add MEMMGR.LIB as this will be done implicitly for you //--------------------------------------------------------------------------- #pragma argsused int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved) { return 1; } //--------------------------------------------------------------------------- extern "C" __declspec(dllexport) int __stdcall Calc(int a, int b) //导出函数 { return a+b; } //---------------------------------------------------------------------------
保存工程为DLLs,编译,就会在工程目录下生成DLLs.dll(大小应该是8K),同时还会自动在同一目录下生成DLLs.lib静态库,如果没有生成,请自己手动使用implib.exe工具生成(使用方法见本文说明)。
(2).导出函数(使用VCL) 使用BCB DLL向导建立一个工程,选择使用VCL支持,新建立一个窗体(采用默认名称TForm1)存为Unit1.cpp,设置窗体大小为一般OKCANCEL 对框的大小(这里设为277*119),在窗体上添加两个按钮:Button1标签为"确定",ModalResult为mrOk,Button2标签为 "取消",ModalResult为mrCancel; 然后在DLL主程序中引用刚才建立的窗体,并添加导出函数,代码如下:
//--------------------------------------------------------------------------- #include #include #pragma hdrstop //--------------------------------------------------------------------------- // Important note about DLL memory management when your DLL uses the // static version of the RunTime Library: // // If your DLL exports any functions that pass String objects (or structs/ // classes containing nested Strings) as parameter or function results, // you will need to add the library MEMMGR.LIB to both the DLL project and // any other projects that use the DLL. You will also need to use MEMMGR.LIB // if any other projects which use the DLL will be performing new or delete // operations on any non-TObject-derived classes which are exported from the // DLL. Adding MEMMGR.LIB to your project will change the DLL and its calling // EXE's to use the BORLNDMM.DLL as their memory manager. In these cases, // the file BORLNDMM.DLL should be deployed along with your DLL. // // To avoid using BORLNDMM.DLL, pass string information using "char *" or // ShortString parameters. // // If your DLL uses the dynamic version of the RTL, you do not need to // explicitly add MEMMGR.LIB as this will be done implicitly for you //--------------------------------------------------------------------------- #include "Unit.h" //引用设计的窗体 #pragma argsused int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved) { return 1; } //--------------------------------------------------------------------------- extern "C" __declspec(dllexport) int __stdcall UserClick(void) //导出函数 { TForm1 *Form1 = new TForm1(NULL); if(Form1->ShowModal() == mrOk) { delete Form1; return 1; } else { delete Form1; return 0; } } //---------------------------------------------------------------------------
//--------------------------------------------------------------------------- #include //--------------------------------------------------------------------------- // Important note about DLL memory management when your DLL uses the // static version of the RunTime Library: // // If your DLL exports any functions that pass String objects (or structs/ // classes containing nested Strings) as parameter or function results, // you will need to add the library MEMMGR.LIB to both the DLL project and // any other projects that use the DLL. You will also need to use MEMMGR.LIB // if any other projects which use the DLL will be performing new or delete // operations on any non-TObject-derived classes which are exported from the // DLL. Adding MEMMGR.LIB to your project will change the DLL and its calling // EXE's to use the BORLNDMM.DLL as their memory manager. In these cases, // the file BORLNDMM.DLL should be deployed along with your DLL. // // To avoid using BORLNDMM.DLL, pass string information using "char *" or // ShortString parameters. // // If your DLL uses the dynamic version of the RTL, you do not need to // explicitly add MEMMGR.LIB as this will be done implicitly for you //--------------------------------------------------------------------------- #pragma argsused int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void* lpReserved) { return 1; } //--------------------------------------------------------------------------- __declspec(dllexport) __stdcall class TTest{ //声明导出类 int a,b; public: void __stdcall SetValue(int x, int y); int __stdcall Calc(void); }; //--------------------------------------------------------------------------- void __stdcall TTest::SetValue(int x, int y) //类的实现 { this->a = x; this->b = y; } //--------------------------------------------------------------------------- int __stdcall TTest::Calc(void) //类的实现 { return this->a + this->b; } //---------------------------------------------------------------------------
====
一. 编写 DLL
File/New/Dll 生成 Dll 的向导,然后可以添加导出函数和导出类
导出函数:extern "C" __declspec(dllexport) ExportType FunctionName(Parameter)
导出类:class __declspec(dllexport) ExportType ClassName{...}
例子:(说明:只是生成了一个 DLL.dll )
#include "DllForm.h" // TDllFrm 定义 USERES("Dll.res"); USEFORM("DllForm.cpp", DllFrm); class __declspec(dllexport) __stdcall MyDllClass { //导出类 public: MyDllClass(); void CreateAForm(); TDllFrm* DllMyForm; }; TDllFrm* DllMyForm2; extern "C" __declspec(dllexport) __stdcall void CreateFromFunct();//导出函数 //--------------------------------------------------------------------------- int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void*) { return 1; } //--------------------------------------------------------------------------- MyDllClass::MyDllClass() { } void MyDllClass::CreateAForm() { DllMyForm = new TDllFrm(Application); DllMyForm->Show(); } //--------------------------------------------------------------------------- void __stdcall CreateFromFunct() { DllMyForm2 = new TDllFrm(Application); DllMyForm2->Show(); }
二. 静态调用 DLL
使用 $BCB path\Bin\implib.exe 生成 Lib 文件,加入到工程文件中,将该文件拷贝到当前目录,使用 implib MyDll.lib MyDll.dll 生成。
// Unit1.h // TForm1 定义 #include "DllForm.h" // TDllFrm 定义 //--------------------------------------------------------------------------- __declspec(dllimport) class __stdcall MyDllClass { public: MyDllClass(); void CreateAForm(); TDllFrm* DllMyForm; }; extern "C" __declspec(dllimport) __stdcall void CreateFromFunct(); class TForm1 : public TForm{} // Unit1.cpp // TForm1 实现 void __fastcall TForm1::Button1Click(TObject *Sender) { // 导出类实现,导出类只能使用静态方式调用 DllClass = new MyDllClass(); DllClass->CreateAForm(); } //--------------------------------------------------------------------------- void __fastcall TForm1::Button2Click(TObject *Sender) { // 导出函数实现 CreateFromFunct(); } //--------------------------------------------------------------------------- void __fastcall TForm1::FormClose(TObject *Sender, TCloseAction &Action) { delete DllClass; }
三. 动态调用 DLL
// Unit1.h class TForm1 : public TForm { private: // User declarations void (__stdcall *CreateFromFunct)(); } // Unit1.cpp // TForm1 HINSTANCE DLLInst = NULL; void __fastcall TForm1::Button2Click(TObject *Sender) { if( NULL == DLLInst ) DLLInst = LoadLibrary("DLL.dll"); //上面的 Dll if (DLLInst) { CreateFromFunct = (void (__stdcall*)()) GetProcAddress(DLLInst, "CreateFromFunct"); if (CreateFromFunct) CreateFromFunct(); else ShowMessage("Could not obtain function pointer"); } else ShowMessage("Could not load DLL.dll"); } void __fastcall TForm1::FormClose(TObject *Sender, TCloseAction &Action) { if ( DLLInst ) FreeLibrary (DLLInst); }
四. DLL 作为 MDIChild (子窗体) 【只编写动态调用的例子】
实际上,调用子窗体的 DLL 时,系统只是检查应用程序的 MainForm 是否为 fsMDIForm 的窗体,这样只要把调用程序的 Application 的 Handle 传递给 DLL 的 Application 即可;同时退出 DLL 时也要恢复。
Application
// MDIChildPro.cpp // Dll 实现 CPP
#include "unit1.h" // TForm1 定义 TApplication *SaveApp = NULL; int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void*) { if ( (reason==DLL_PROCESS_DETACH) && SaveApp ) Application = SaveApp ; // 恢复 Application return 1; } extern "C" __declspec(dllexport) __stdcall void TestMDIChild( //1024X768 TApplication* mainApp, LPSTR lpCaption) { if ( NULL == SaveApp ) // 保存 Application,传递 Application { SaveApp = Application; Application = mainApp; } // lpCaption 为子窗体的 Caption TForm1 *Form1 = new TForm1 ( Application, lpCaption ); Form1->Show(); }
注:上面的程序使用 BCB 3.0 编译成功
五. BCB 调用 VC 编写的 DLL
1. 名字分解:
没有名字分解的函数
TestFunction1 // __cdecl calling convention
@TestFunction2 // __fastcall calling convention
TESTFUNCTION3 // __pascal calling convention
TestFunction4 // __stdcall calling convention
有名字分解的函数
@TestFunction1$QV // __cdecl calling convention
@TestFunction2$qv // __fastcall calling convention
TESTFUNCTION3$qqrv // __apscal calling convention
@TestFunction4$qqrv // __stdcall calling convention
使用 extern "C" 不会分解函数名
使用 Impdef MyLib.def MyLib.DLL 生成 def 文件查看是否使用了名字分解
2. 调用约定:
__cdecl 缺省
是 Borland C++ 的缺省的 C 格式命名约定,它在标识符前加一下划线,以保留它原来所有的全程标识符。参数按最右边参数优先的原则传递给栈,然后清栈。
extaern "C" bool __cdecl TestFunction();
在 def 文件中显示为 TestFunction @1
注释: @1 表示函数的顺序数,将在“使用别名”时使用。
__pascal Pascal格式
这时函数名全部变成大写,第一个参数先压栈,然后清栈。
TESTFUNCTION @1 //def file
__stdcall 标准调用
最后一个参数先压栈,然后清栈。
TestFunction @1 //def file
__fastcall 把参数传递给寄存器
第一个参数先压栈,然后清栈。
@TestFunction @1 //def file
3. 解决调用约定:
Microsoft 与 Borland 的 __stdcall 之间的区别是命名方式。 Borland 采用__stdcall 的方式去掉了名字起前的下划线。 Microsoft 则是在前加上下划线,在后加上 @ ,再后跟为栈保留的字节数。字节数取决于参数在栈所占的空间。每一个参数都舍入为 4 的倍数加起来。这种 Miocrosoft 的 DLL 与系统的 DLL 不一样。
4. 使用别名:
使用别名的目的是使调用文件 .OBJ 与 DLL 的 .DEF 文件相匹配。如果还没有.DEF 文件,就应该先建一个。然后把 DEF 文件加入 Project。使用别名应不断修改外部错误,如果没有,还需要将 IMPORTS 部分加入 DEF 文件。
IMPORTS
TESTFUNCTIOM4 = DLLprj.TestFunction4
TESTFUNCTIOM5 = DLLprj.WEP @500
TESTFUNCTIOM6 = DLLprj.GETHOSTBYADDR @51
这里需要说明的是,调用应用程序的 .OBJ 名与 DLL 的 .DEF 文件名是等价的,而且总是这样。甚至不用考虑调用约定,它会自动匹配。在前面的例子中,函数被说明为 __pascal,因此产生了大写函数名。这样链接程序不会出错。
5. 动态调用例子
VC DLL 的代码如下:
extern "C" __declspec(dllexport) LPSTR __stdcall BCBLoadVCWin32Stdcall() { static char strRetStdcall[256] = "BCB Load VC_Win32 Dll by __stdcall mode is OK!"; return strRetStdcall; } extern "C" __declspec(dllexport) LPSTR __cdecl BCBLoadVCWin32Cdecl() { static char strRetCdecl[256] = "BCB Load VC_Win32 Dll by __cdecl mode is OK!"; return strRetCdecl; } extern "C" __declspec(dllexport) LPSTR __fastcall BCBLoadVCWin32Fastcall() { static char strRetFastcall[256] = "BCB Load VC_Win32 Dll by __fastcall mode is OK!"; return strRetFastcall; }
其实动态调用与调用 BCB 编写的 DLL 没有区别,关键是查看 DLL 的导出函数名字。可以使用 tdump.exe(BCB工具) 或者 dumpbin.exe(VC工具) 查看
tdump -ee MyDll.dll >1.txt (查看 1.txt 文件即可)
由于 VC6 不支持 __pascall 方式,下面给出一个三种方式的例子:
void __fastcall TForm1::btnBLVCWin32DynClick(TObject *Sender) { /*cmd: tdbump VCWin32.dll >1.txt Turbo Dump Version 5.0.16.4 Copyright (c) 1988, 1998 Borland International Display of File VCWIN32.DLL EXPORT ord:0000='BCBLoadVCWin32Fastcall::' EXPORT ord:0001='BCBLoadVCWin32Cdecl' EXPORT ord:0002='_BCBLoadVCWin32Stdcall@0' */ if ( !DllInst ) DllInst = LoadLibrary ( "VCWin32.dll" ); if ( DllInst ) { BCBLoadVCWin32Stdcall = (LPSTR (__stdcall *) () ) GetProcAddress ( DllInst, "_BCBLoadVCWin32Stdcall@0" ); //VC Dll // GetProcAddress ( DllInst, "BCBLoadVCWin32Stdcall" ); //BCB Dll if ( BCBLoadVCWin32Stdcall ) { ShowMessage( BCBLoadVCWin32Stdcall() ); } else ShowMessage ( "Can't find the __stdcall Function!" ); BCBLoadVCWin32Cdecl = (LPSTR (__cdecl *) () ) GetProcAddress ( DllInst, "BCBLoadVCWin32Cdecl" ); if ( BCBLoadVCWin32Cdecl ) { ShowMessage( BCBLoadVCWin32Cdecl() ); } else ShowMessage ( "Can't find the __cdecl Function!" ); //Why?不是 'BCBLoadVCWin32Fastcall::',而是 '@BCBLoadVCWin32Fastcall@0'? BCBLoadVCWin32Fastcall = (LPSTR (__fastcall *) () ) //GetProcAddress ( DllInst, "BCBLoadVCWin32Fastcall::" ); GetProcAddress ( DllInst, "@BCBLoadVCWin32Fastcall@0" ); if ( BCBLoadVCWin32Fastcall ) { ShowMessage( BCBLoadVCWin32Fastcall() ); } else ShowMessage ( "Can't find the __fastcall Function!" ); } else ShowMessage ( "Can't find the Dll!" ); }
6. 静态调用例子
静态调用有点麻烦,从动态调用中可以知道导出函数的名字,但是直接时(加入 lib 文件到工程文件)
Linker 提示不能找到函数的实现
从 4 看出,可以加入 def 文件连接(可以通过 impdef MyDll.def MyDll.dll 获得导出表)。
建立与 DLL 文件名一样的 def 文件与 lib 文件一起加入到工程文件。
上面的 DLL(VCWIN32.dll) 的 def 文件为(VCWIN32.def):
LIBRARY VCWIN32.DLL
IMPORTS
@BCBLoadVCWin32Fastcall = VCWIN32.@BCBLoadVCWin32Fastcall@0
_BCBLoadVCWin32Cdecl = VCWIN32.BCBLoadVCWin32Cdecl
BCBLoadVCWin32Stdcall = VCWIN32._BCBLoadVCWin32Stdcall@0
对应的函数声明和实现如下:
extern "C" __declspec(dllimport) LPSTR __fastcall BCBLoadVCWin32Fastcall();
extern "C" __declspec(dllimport) LPSTR __cdecl BCBLoadVCWin32Cdecl();
extern "C" __declspec(dllimport) LPSTR __stdcall BCBLoadVCWin32Stdcall();
void __fastcall TfrmStatic::btnLoadDllClick(TObject *Sender)
{
ShowMessage ( BCBLoadVCWin32Fastcall() );
ShowMessage ( BCBLoadVCWin32Cdecl() );
ShowMessage ( BCBLoadVCWin32Stdcall() );
}
注意:在 BCB 5.0 中,可能直接按下 F9 是不能通过 Linker 的,请先 Build 一次。上面的程序使用 BCB 5.0 与 VC6.0 编译成功