MFC:动态链接库

动态链接库

1.01 显式链接DLL

/* 创建dll类 */
int fnTest(void);

#include "stdafx.h"
#include "Test.h"

BOOL APIENTRY DllMain( HANDLE hModule, 
                       DWORD  ul_reason_for_call, 
                       LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
		case DLL_PROCESS_ATTACH:
			nCount++;
			break;
		case DLL_PROCESS_DETACH:
			nCount--;
			break;
		default:
			break;
	}

    return TRUE;
}

int fnTest(void)
{
	return 100;
}

/* test.def */
; Test.def : Declares the module parameters for the DLL.

LIBRARY      "Test"
DESCRIPTION  'Test Windows Dynamic Link Library'

EXPORTS
	fnTest

/* 动态加载 */
void CDemoDlg::OnTest()
{
	//加载DLL
	HINSTANCE hModule = LoadLibrary(_T("test.dll"));
	if (hModule == NULL)
	{
		AfxMessageBox(_T("test.dll加载失败\n"));
		return;
	}

	typedef int (_cdecl *FUNTEST)(void);
	FUNTEST pfnTest;

	//获得导出函数的地址
	pfnTest = (FUNTEST)GetProcAddress(hModule, "fnTest");

	//调用导出函数
	if (pfnTest != NULL)
	{
		/* 函数调用 */
		int nValue = (*pfnTest)();
		CString strMessage = _T("");
		strMessage.Format(_T("%d"), nValue);
		AfxMessageBox(strMessage);
	}
	else
	{
		int n = GetLastError();
		TRACE(_T("LastError:%d\n"), n);	
	}

	//释放DLL
	FreeLibrary(hModule);
}

1.02 显式链接DLL

//DLL导出函数的头文件
#include "Test.h"
//DLL的导入库lib文件
#pragma comment(lib, "test.lib")

void CDemoDlg::OnTest()
{
	//直接调用DLL的导出函数
	int nValue = fnTest();
}