通过时间循环QEventLoop实现http请求

    QNetworkAccessManager *manager = new QNetworkAccessManager();
    QNetworkReply *reply = manager->get(QNetworkRequest(QUrl(url)));
    QByteArray responseData;
    QEventLoop eventLoop;

    QObject::connect(manager, SIGNAL(finished(QNetworkReply *)), &eventLoop, SLOT(quit()));

    eventLoop.exec();
    responseData = reply->readAll();

当调用事件的exec()的时候，程序就会在exec()里面无限循环，不会执行后面的代码，除非程序调用exit()从exec()里面跳出来。