我正在构建一个从服务器下载zip文件的应用程序。我使用QNetworkAccessManager和QNetworkReply对象来这样做。一切正常，除了服务器由于某种原因断开连接时，我从未收到错误信号。我将QNetworkReply对象与信号'error（QNetworkReply :: NetworkError）'连接到了错误插槽，但没有任何反应。如何处理“服务器停机”情况？
reply = qnam->get(QNetworkRequest(url));
connect(reply, SIGNAL(finished()), this, SLOT(httpFinished()));
connect(reply, SIGNAL(readyRead()), this, SLOT(httpReadyRead()));
connect(reply, &QNetworkReply::downloadProgress, this, &HTTPClient::networkReplyProgress);
connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(error(QNetworkReply::NetworkError)));