一种可靠的 DLL 接口实现方案 - c++编程基础

[cpp]
// Service.h, DLL定义(供实现方、调用方使用)
////////////////////////////////////////////////////////////////////////////////
#ifdef SERVICE_EXPORTS
#define SERVICE_API extern "C" __declspec(dllexport)
#else
#define SERVICE_API
//#define SERVICE_API extern "C" __declspec(dllimport)
#endif

interface IService
{
public:
IService() {}
virtual ~IService() {}

public:
virtual void Start() = 0;
virtual void Stop() = 0;
};

typedef IService *(*CreateInstance_t)();
typedef void (*DestroyInstance_t)(IService *pInst);

SERVICE_API IService *CreateInstance();
SERVICE_API void DestroyInstance(IService *pInst);

// Service.cpp, DLL实现
////////////////////////////////////////////////////////////////////////////////
#include "Service.h"
class CService : public IService
{
public:
CService();
virtual ~CService();

public:
virtual void Start();
virtual void Stop();

private:
//.....
};

CService::CService()
{
}

CService::~CService()
{
}

void CService::Start()
{
}

void CService::Stop()
{

}

IService *CreateInstance()
{
return new CService();
}

void DestroyInstance(IService *pInst)
{
if (!pInst) return;
delete pInst;
}

SERVICE_API HRESULT WINAPI DllRegisterServer()
{
//CMD> regsvr32.exe Service.dll 时需要执行的安装代码
return S_OK;
}

SERVICE_API HRESULT WINAPI DllUnregisterServer()
{
//CMD> regsvr32.exe /u Service.dll 时需要执行的卸载代码
return S_OK;
}

// Demo.cpp, DLL调用
////////////////////////////////////////////////////////////////////////////////
#include "Service.h"
int WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
{
HMODULE hDll = LoadLibraryA("Service.dll");
if (hDll)
{
CreateInstance_t pfnCreateInstance =
(CreateInstance_t)GetProcAddress(hDll, "CreateInstance");
DestroyInstance_t pfnDestroyInstance =
(DestroyInstance_t)GetProcAddress(hDll, "DestroyInstance");
if (pfnCreateInstance && pfnDestroyInstance)
{
IService *pInst = pfnCreateInstance();

if (pInst)
{
pInst->Start();
pInst->Stop();

pfnDestroyInstance(pInst);
}
}

FreeLibrary(hDll);
}

return 0;
}