//media_player.h
#ifndef MEDIAPLAYER_H
#define MEDIAPLAYER_H
#include <string>
class MediaPlayer
{
public:
    virtual void play(std::string audioType, std::string fileName){
    };
};
#endif // MEDIAPLAYER_H
//advance_media_player.h
#ifndef ADVANCE_MEDIA_PLAYER_H
#define ADVANCE_MEDIA_PLAYER_H
#include <string>
class AdvancedMediaPlayer{
public:
    virtual void playVlc(std::string fileName){
    };
    virtual void playMp4(std::string fileName){
    };
};
#endif // ADVANCE_MEDIA_PLAYER_H
//media_adapter.h
#ifndef MEDIA_ADAPTER_H
#define MEDIA_ADAPTER_H
#include "advance_media_player.h"
#include "media_player.h"
#include "vlc_player.h"
#include "mp4_player.h"
class MediaAdapter :public MediaPlayer
{
private:
    AdvancedMediaPlayer* advancedMusicPlayerPtr;
public:
    MediaAdapter(std::string audioType){
        if(audioType == ("vlc") ){
            advancedMusicPlayerPtr = new VlcPlayer;
        }else if (audioType == "mp4"){
            advancedMusicPlayerPtr = new Mp4Player;
        }
    }
    void play(std::string audioType, std::string fileName) override{
        if(audioType == ("vlc") ){
            advancedMusicPlayerPtr->playVlc(fileName);
        }else if (audioType == "mp4"){
            advancedMusicPlayerPtr->playMp4(fileName);
        }
    }
};
#endif // MEDIA_ADAPTER_H
//mp4_player.h
#ifndef MP4_PLAYER_H
#define MP4_PLAYER_H
#include "advance_media_player.h"
#include <iostream>
class Mp4Player :public AdvancedMediaPlayer
{
public:
    void playMp4(std::string fileName) override{
        std::cout<<"Playing mp4 file. Name:"<<fileName<<std::endl;
    }
    void playVlc(std::string fileName) override{
    }
};
#endif // MP4_PLAYER_H
//vlc_player.h
#ifndef VLC_PLAYER_H
#define VLC_PLAYER_H
#include "advance_media_player.h"
#include <iostream>
class VlcPlayer :public AdvancedMediaPlayer
{
public:
    void playMp4(std::string fileName) override{
    }
    void playVlc(std::string fileName) override{
        std::cout<<"Playing vlc file. Name:"<<fileName<<std::endl;
    }
};
#endif // VLC_PLAYER_H
//audio_player.h
#ifndef AUDIO_PLAYER_H
#define AUDIO_PLAYER_H
#include "media_player.h"
#include "media_adapter.h"
#include "mp4_player.h"
class AudioPlayer :public MediaPlayer
{
private:
    MediaAdapter* mediaAdapterPtr;
public:
    void play(std::string audioType, std::string fileName) override{
        if(audioType == "vlc" || audioType == "mp4"){
            mediaAdapterPtr = new MediaAdapter(audioType);
            mediaAdapterPtr->play(audioType,fileName);
        }else if (audioType == "mp3"){
            std::cout<<"Playing mp3 file. Name: "<<fileName<<std::endl;
        }else{
           std::cout<<"invalid "<<std::endl;
        }
    }
};
#endif // AUDIO_PLAYER_H
//main,cpp
#include <iostream>
#include "audio_player.h"
using namespace std;
int main()
{
    AudioPlayer* audioPlayer = new AudioPlayer();
    audioPlayer->play("mp3", "beyond the horizon.mp3");
    audioPlayer->play("mp4", "alone.mp4");
    audioPlayer->play("vlc", "far far away.vlc");
    audioPlayer->play("avi", "mind me.avi");
    return 0;
}
输出结果：
Playing mp3 file. Name: beyond the horizon.mp3
Playing mp4 file. Name:alone.mp4
Playing vlc file. Name:far far away.vlc
invalid