求索阁

/功能：    根据一个URL地址将数据保存到指定路径下，支持断点续传

//参数：    url            --需要访问的URL地址

//         SavePath       --需要保存的路径

//DownedSize 已经下载的大小

// totalSize 文件总大小

//返回值：  ture --成功 false --失败

bool HttpGet::DownFile(const QUrl &url,const QString &SavePath,int DownedSize,int totalSize)

{ //创建父文件夹

  QString curPath=QApplication::applicationDirPath()+"/Files";

  if(!QDir(curPath).exists())

  {

   QDir photoDir;

   photoDir.mkdir(curPath);

  }

//创建子文件夹

    if(!QDir(SavePath).exists())

    {

     QDir photoDir;

     photoDir.mkdir(SavePath);

    }

    QNetworkRequest qheader;

    qheader.setUrl(url);

    QString Range="bytes "+QString::number(DownedSize)+"-";//告诉服务器从DownedSize起开始传输

    qheader.setRawHeader("Range",Range.toAscii());

        QNetworkAccessManager manager;

        //参考 http://www.qtforum.org/article/31355/qnetworkaccessmanager-using-custom-headers-to-download-a-file.html

        QEventLoop loop;

        //QNetworkReply *reply = manager.get(QNetworkRequest(url));

        QNetworkReply *reply = manager.get(QNetworkRequest(qheader));

        QObject::connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));

        loop.exec();

        QFileInfo fileInfo=url.path();

        QFile file(SavePath+fileInfo.fileName());

        file.open(QIODevice::WriteOnly);

        file.write(reply->readAll());

        delete reply;

        return true;

}

使用

  getter.DownFile(QUrl(FileUrl),QString(CurrentPath),0,FileSize);

  QObject::connect(&getter, SIGNAL(finished()),  SLOT(quit()));

断点续传原理：需要在HTTP请求的header中添加Rang节,告诉服务器从文件的那个位置开始传输.格式为bytes 开始传输的位置-