Dll创建及调用

隐式链接

 

I：DLL创建

a：创建一个Smart Device的Win32项目

 

b：选择WM6的SDK

 

c：选择Dll并导出

 

d：visual studio 自动生成的代码，这里加上了HelloWorld函数。

 

MyDll.cpp：

#include "stdafx.h"

#include "MyDll.h"

#include <windows.h>

#include <commctrl.h>

 

BOOL APIENTRY DllMain( HANDLE hModule,

                       DWORD  ul_reason_for_call,

                       LPVOID lpReserved

                        )

{

     switch (ul_reason_for_call)

     {

     case DLL_PROCESS_ATTACH:

     case DLL_THREAD_ATTACH:

     case DLL_THREAD_DETACH:

     case DLL_PROCESS_DETACH:

         break;

     }

    return TRUE;

}

 

// This is an example of an exported variable

MYDLL_API int nMyDll=0;

 

// This is an example of an exported function.

MYDLL_API int fnMyDll(void)

{

     return 42;

}

 

// This is the constructor of a class that has been exported.

// see MyDll.h for the class definition

CMyDll::CMyDll()

{

     return;

}

 

MYDLL_API void HelloWorld(void)

{

     MessageBox (NULL, TEXT ("Hello World"), TEXT ("HelloWorld"), MB_OK);

}

 

MyDll.h：

// The following ifdef block is the standard way of creating macros which make exporting

// from a DLL simpler. All files within this DLL are compiled with the MYDLL_EXPORTS

// symbol defined on the command line. this symbol should not be defined on any project

// that uses this DLL. This way any other project whose source files include this file see

// MYDLL_API functions as being imported from a DLL, whereas this DLL sees symbols

// defined with this macro as being exported.

#ifdef MYDLL_EXPORTS

#define MYDLL_API __declspec(dllexport)

#else

#define MYDLL_API __declspec(dllimport)

#endif

 

// This class is exported from the MyDll.dll

class MYDLL_API CMyDll {

public:

     CMyDll(void);

     // TODO: add your methods here.

};

 

extern MYDLL_API int nMyDll;

 

MYDLL_API int fnMyDll(void);

 

MYDLL_API void HelloWorld(void);

 

头文件 MyDll.h还将用于调用MyDll.dll的文件，MYDLL_API __declspec(dllexport)用于MyDll.cpp,其中MYDLL_EXPORTS 定义在：

 

 

 

这样当调用该Dll的文件没有定义MYDLL_EXPORTS,则使用#define MYDLL_API __declspec(dllimport).

e：编译后将生成MyDll.dll和MyDll.lib，其中MyDll.lib用于调用该Dll的文件编译时使用，可以用dumpbin -exports查看该Dll导出的函数：

 

 

 

 

II：DLL调用

a：创建一个控制台程序DllTest，并将上面生成的Mydll.lib和MyDll.h拷贝到该项目的目录下

b：在link的input中加入MyDll.lib：

 

c：将MyDll.dll拷贝包SDk模拟器的Program Files/DllTest目录下，否则运行时找不到MyDll.dll会报错无法运行

d：运行Debug，就可以看到效果了：

 

 

---

动态加载

 

1：新建一个Smart Device的Win32项目

2：创建一个Dll，不要导出符号

3：MyDll_Def.cpp:

// MyDll_Def.cpp : Defines the entry point for the DLL application.

//

 

#include "stdafx.h"

#include <windows.h>

#include <commctrl.h>

 

BOOL APIENTRY DllMain( HANDLE hModule,

                       DWORD  ul_reason_for_call,

                       LPVOID lpReserved

                        )

{

    return TRUE;

}

 

void HelloWorld(void)

{

     MessageBox (NULL, TEXT ("Hello World"), TEXT ("Hello World"), MB_OK);

}

 

 

4：新建一个def文件，用于导出HelloWorld

LIBRARY  "MyDll_Def"

 

EXPORTS

     HelloWorld

 

5：创建一个DllTest_Def测试程序：

// DllTest_Def.cpp : Defines the entry point for the console application.

//

 

#include "stdafx.h"

#include <windows.h>

#include <commctrl.h>

 

 

int _tmain(int argc, _TCHAR* argv[])

{

     HINSTANCE hInst;

 

     hInst=LoadLibrary(TEXT("MyDll_Def.dll"));

     if(NULL == hInst)  {

         MessageBox (NULL, TEXT ("Hello World"), TEXT ("Load MyDll_Def.dll error"), MB_OK);     

         return -1;

     }

 

     typedef void (*HELLOWORLDPROC)();

     HELLOWORLDPROC HelloWorld=(HELLOWORLDPROC)GetProcAddress(hInst,TEXT("HelloWorld"));

     if(NULL == HelloWorld) {

         MessageBox (NULL, TEXT ("Hello World"), TEXT ("GetProcAddress HelloWorld error"), MB_OK);

         return -1;

     }

 

     HelloWorld();

 

     FreeLibrary(hInst);

 

     return 0;

}

 

LoadLibrary用于动态加载Dll,GetProcAddress用于获取函数指针.

 

6：将MyDll.dll拷贝包SDk模拟器的Program Files/DllTest目录下，否则运行时找不到MyDll.dll会报错无法运行

 

7：运行Debug，就可以看到效果了：