C++加载动态库的形式来实现封装

时间：2023-12-18 08:15:20

目录结构

└── test

    ├── CMakeLists.txt

    ├── base.h                            //设置接口

    ├── drive.cpp                        //具体实现

    └── main.cpp                        //ｔｅｓｔ

CMakeLists.txt

cmake_minimum_required (VERSION 2.8)

project (test)

set(CMAKE_CXX_STANDARD 11)

include_directories(./)

add_library(drive SHARED drive.cpp) #将实现添加为动态库

add_executable(test main.cpp) #将test生成可执行

target_link_libraries(test ${CMAKE_DL_LIBS}) #链接dl库

base.h

#ifndef BASE_H

#define BASE_H

#include <iostream>

#include <memory>

#include <dlfcn.h>

using namespace std;

 //宏用在drive.cpp中生成产生子类对象的函数

#define USE_MAPFUSION_PLUGIN(C) extern "C"{\

    shared_ptr<base> createInstance(){return shared_ptr<base>(new C());}}     

class base;

typedef shared_ptr<base> (*funcCreatClass)();

class base {

public:

    virtual void print() {cout << "base" << endl;}

    static shared_ptr<base> create(const string& plugin) {

        int realFlags = RTLD_LAZY|RTLD_GLOBAL;

        void* handle = dlopen(plugin.c_str(), realFlags);//打开库

        if (!handle) {

            const char* err = dlerror();

            cerr << "Can not open file " << plugin << "since " << err << endl;

            return shared_ptr<base>();

        }

        funcCreatClass createFunc = (funcCreatClass)dlsym(handle, "createInstance");  //加载库中生成子类对象的函数

        if(!createFunc) return shared_ptr<base>();

        else return createFunc();

    }

};

#endif // BASE_H

drive.cpp

#include "base.h"

using namespace std;

class drive : public base {

public:

    virtual void print() {cout << "drive" << endl;}

};

USE_MAPFUSION_PLUGIN(drive)                                            //展开base.h中的宏来生成产生子类对象的函数

main.cpp

#include "base.h"

using namespace std;

int main(int argc, char *argv[])

{

    shared_ptr<base> a = base::create("libdrive.so");

    a->print();

}

运行结果

$ mkdir build

$ cd build

$ camke ..

$ make

$ ./test

///输出

//drive

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