C++制作DLL文件的方法详解

#pragma once
#ifdef MYLIBRARY_EXPORTS
#define MYLIBRARY_api __declspec(dllexport)
#else
#define MYLIBRARY_API __declspec(dllimport)
#endif
 
MYLIBRARY_API int Add(int a, int b);

#include "DllDLL.h"
 
int Add(int a, int b)
{
	return a + b;
}

LIBRARY GeneratrDLL
EXPORTS
Add @1

#include "..\DllDLL\DllDLL.h"
#include <windows.h>
#include <iOStream>
typedef int(*AddFunc)(int, int);
 
int main()
{
	HINSTANCE hinstLib = LoadLibrary(TEXT("DllDLL.dll"));
	if (hinstLib != NULL)
	{
		AddFunc add = (AddFunc)GetProcAddress(hinstLib, "Add");
		if (add != NULL)
		{
			// 调用 DLL 中的函数
			int result = add(1, 2);
			std::cout << result << std::endl;
		}
	}
 
}

// MyInterface.h
#ifndef MY_INTERFACE_H
#define MY_INTERFACE_H
 
class MyInterface
{
public:
	virtual ~MyInterface(){}
	virtual void DoSomething() = 0;
	virtual int GetNumber() = 0;
};
 
class MyImplementation : public MyInterface
{
public:
	virtual void DoSomething() override;
	virtual int GetNumber() override;
};
#endif // MY_INTERFACE_H
 
 
 
 
// MyImplementation.cpp
#include "MyInterface.h"
 
void MyImplementation::DoSomething()
{
	//
}
 
int MyImplementation::GetNumber()
{
	return 49;
}
 
 
 
// MyDLL.h
#ifndef MY_DLL_H
#define MY_DLL_H
 
#ifdef MY_DLL_EXPORTS
#define MY_DLL_API __declspec(dllexport)
#else
#define MY_DLL_API __declspec(dllimport)
#endif
 
#include "MyInterface.h"
 
MY_DLL_API MyInterface* CreateMyObject();
 
#endif // MY_DLL_H
 
 
 
// MyDLL.cpp
#define MY_DLL_EXPORTS
#include "MyDLL.h"
#include "MyInterface.h"
 
 
MyInterface* CreateMyObject()
{
	return new MyImplementation();
}

#include "..\GeneratrDLL\MyInterface.h"
#include <Windows.h>
#include <iostream>
 
int main()
{
	// 加载DLL
	HMODULE hModule = LoadLibrary(L"C:\\Users\\liubw\\source\\repos\\GeneratrDLL\\x64\\Debug\\GeneratrDLL.dll");
 
	if (hModule != NULL)
	{
		// 获取接口
        typedef MyInterface* (*CreateMyObjectFunc)();
		CreateMyObjectFunc fun = (CreateMyObjectFunc)GetProcAddress(hModule, "CreateMyObject");
 
		if (fun != NULL)
		{
			// 使用接口
			MyInterface* myObject = createMyObject();
			myObject->DoSomething();
			int number = myObject->GetNumber();
			std::cout << number << std::endl;
			delete myObject;
		}
		else
		{
			// 无法获取接口
		}
 
		// 卸载DLL
		FreeLibrary(hModule);
	}
	else
	{
		// 无法加载DLL
	}
 
	return 0;
}