http = new QHttp(this);
connect(http, SIGNAL(requestFinished(int, bool)), this, SLOT(requestFinishedSlot(int, bool)));
http->setHost(IP, Port.toUInt());
http->get(QString("http://%1:%2/file").arg(IP).arg(Port), file);
变量http和file时类成员变量,在get提交请求时,信号requestFinished触发槽requestFinishedSlot两次,