2015.12.19
在此前完成的一个APP中有下载网络视频、音乐的客户需求，我自己封装了一个类。希望能够帮到大家。我使用的cocos2d-x的版本是3.4。

Downloader

这是cocos2d封装的一个用于下载网络数据的类，支持同步以及异步下载。更详细的类方法大家可以进去看。
使用时加上头文件。#include “extensions/assets-manager/Downloader.h”

实际调用：

第一个参数：音乐名的字符串，例如”song.mp3”
第二个参数：连接地址，例如”www.fffffffffffff.mp3”
HttpDownLoadingHelper::getInstance()->DownloadMusicToSandBox(“song.mp3”,“www.fffffffffffff.mp3”);

以下将我封装的HttpDownLoadingHelper类源码贴上,下载音乐和下载视频的用法是一样。

HttpDownLoadingHelper.h

#include <stdio.h>
#include "extensions/assets-manager/Downloader.h"
#include "cocos2d.h"
USING_NS_CC;

typedef std::function<void(int progress)> myProgressCallback;

class HttpDownLoadingHelper : public Node
{
public:
    virtual bool init();
    CREATE_FUNC(HttpDownLoadingHelper);
    static HttpDownLoadingHelper *getInstance();
public:
    //video
    void DownloadVideoToSandBox(std::string videoNameStirng,std::string urlLink);
    //music
    void DownloadMusicToSandBox(std::string musicNameStirng,std::string urlLink);

private:
    //video
    void errorCallback(const cocos2d::extension::Downloader::Error& error);
    void VideoprogressCallback(double totalToDownload,double nowDownloaded,const std::string& url,const std::string& customId);
    void VideosuccessCallback(const std::string& url,const std::string& path,const std::string& customId);

   //music
    void MusicprogressCallback(double totalToDownload,const std::string& customId);
    void MusicerrorCallback(const cocos2d::extension::Downloader::Error& error);
    void MusicsuccessCallback(const std::string& url,const std::string& customId);

private:
    std::shared_ptr<cocos2d::extension::Downloader> _myVideoDownloader;
    std::shared_ptr<cocos2d::extension::Downloader> _myMusicDownloader;
};

HttpDownLoadingHelper.cpp

#include "HttpDownLoadingHelper.hpp"
#include "XMLUIVideoPlayer.hpp"
#include "XMLUIMusicPlayer.hpp"
static HttpDownLoadingHelper *g_instance = NULL;
//static int g_imageCount = 1;

HttpDownLoadingHelper *HttpDownLoadingHelper::getInstance()
{
    if (g_instance == NULL) {
        g_instance = HttpDownLoadingHelper::create();
        g_instance->retain();
    }
    return g_instance;
}

bool HttpDownLoadingHelper::init()
{
    if ( !Node::init() )
    {
        return false;
    }

    return true;
}
void HttpDownLoadingHelper::DownloadVideoToSandBox(std::string videoNameStirng,std::string urlLink)
{
    _myVideoDownloader = std::shared_ptr<cocos2d::extension::Downloader>(new cocos2d::extension::Downloader);
// std::shared_ptr<cocos2d::extension::Downloader> myDownloader(new cocos2d::extension::Downloader);

    _myVideoDownloader->setErrorCallback(std::bind(&HttpDownLoadingHelper::errorCallback,g_instance,std::placeholders::_1));

    _myVideoDownloader->setProgressCallback(std::bind(&HttpDownLoadingHelper::VideoprogressCallback,std::placeholders::_1,std::placeholders::_2,std::placeholders::_3,std::placeholders::_4));

    _myVideoDownloader->setSuccessCallback(std::bind(&HttpDownLoadingHelper::VideosuccessCallback,std::placeholders::_3));

    _myVideoDownloader->setConnectionTimeout(5);

    std::string path = FileUtils::getInstance()->getWritablePath() + videoNameStirng;

    std::string remote = urlLink;

    cocos2d::log("Downloading '%s' into '%s'",remote.c_str(),path.c_str());

    _myVideoDownloader->downloadAsync(remote,path,videoNameStirng);
}

void HttpDownLoadingHelper::errorCallback(const cocos2d::extension::Downloader::Error& error)
{
    cocos2d::log("error downloading: %s - %s",error.url.c_str(),error.message.c_str());
}

void HttpDownLoadingHelper::VideoprogressCallback(double totalToDownload,double nowDownloaded,const std::string& url,const std::string& customId)
{
    cocos2d::log("%s",customId.c_str());
    cocos2d::log("video(%s) download progress: %d%% - %s",customId.c_str(),(int)((nowDownloaded/totalToDownload)*100),url.c_str());
    XMLUIVideoPlayer::SetDownloadProgress({
        MAX(1,static_cast<float>((int)((nowDownloaded/totalToDownload)*100))),customId
    });
}

void HttpDownLoadingHelper::VideosuccessCallback(const std::string& url,const std::string& path,const std::string& customId)
{
    cocos2d::log("download finished: %s",path.c_str());
}

//music
void HttpDownLoadingHelper::DownloadMusicToSandBox(std::string musicNameStirng,std::string urlLink)
{
    _myMusicDownloader = std::shared_ptr<cocos2d::extension::Downloader>(new cocos2d::extension::Downloader);

    _myMusicDownloader->setErrorCallback(std::bind(&HttpDownLoadingHelper::MusicerrorCallback,std::placeholders::_1));

    _myMusicDownloader->setProgressCallback(std::bind(&HttpDownLoadingHelper::MusicprogressCallback,std::placeholders::_4));

    _myMusicDownloader->setSuccessCallback(std::bind(&HttpDownLoadingHelper::MusicsuccessCallback,std::placeholders::_3));

    _myMusicDownloader->setConnectionTimeout(5);

    std::string path = FileUtils::getInstance()->getWritablePath() + musicNameStirng;

    std::string remote = urlLink;

    cocos2d::log("Downloading '%s' into '%s'",path.c_str());

    _myMusicDownloader->downloadAsync(remote,musicNameStirng);

}
void HttpDownLoadingHelper::MusicprogressCallback(double totalToDownload,const std::string& customId)
{
    cocos2d::log("music(%s) download progress: %d%% - %s",url.c_str());

    XMLUIMusicPlayer::MusicSetDownloadProgress({
        MAX(1,customId
    });
}
void HttpDownLoadingHelper::MusicerrorCallback(const cocos2d::extension::Downloader::Error& error)
{
    cocos2d::log("error downloading: %s - %s",error.message.c_str());

}
void HttpDownLoadingHelper::MusicsuccessCallback(const std::string& url,path.c_str());
}