关键代码

void DownloadTask::StartDownload(const QUrl url,QFile *file,qint64 startPoint/* =0 */,qint64 endPoint/* =-1 */)
{if( NULL == file )return;m_HaveDoneBytes = 0;m_StartPoint = startPoint;m_EndPoint = endPoint;m_File = file;//根据HTTP协议，写入RANGE头部，说明请求文件的范围QNetworkRequest qheader;qheader.setUrl(url);QString range;range.asprintf(";Bytes=%lld-%lld;", m_StartPoint, m_EndPoint);qheader.setRawHeader(";Range", range.toLatin1());//开始下载qDebug() << "Part " << m_Index << "start download";m_Reply = m_Qnam.get(QNetworkRequest(qheader));connect(m_Reply, SIGNAL(finished()),this, SLOT(FinishedSlot()));connect(m_Reply, SIGNAL(readyRead()),this, SLOT(HttpReadyRead()));
}

效果 

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创作不易，小小的支持一下吧！