Very simple C++ question - synchronous file download

SumRandomGuy

I've got this very simple FileDownloader class. What would be the best way to make my program pause while the download is happening? It's downloading a configuration file and I'd rather it wait for the download to complete.

Thanks!

@#include "filedownloader.h"

FileDownloader::FileDownloader(QObject *parent) :
QObject(parent)
{
http = new QHttp(this);
connect(http, SIGNAL(requestFinished(int,bool)), this, SLOT(requestFinished(int,bool)));

downloadComplete = false;
downloadStatus = NOTHING;

}

void FileDownloader::startDownload()
{
if (Host.isNull() || LocalFile.isNull() || RemoteFile.isNull())
return;

http->setHost(Host);
http->get(RemoteFile);
downloadComplete = false;
downloadStatus = INPROGRESS;

}

bool FileDownloader::isDownloadComplete()
{
return downloadComplete;
}

void FileDownloader::requestFinished(int id, bool error)
{
if (error) {
qDebug() << "Error: ";
downloadStatus = ERROR;

} else {
    qDebug() << "OK";
    QFile *DestFile = new QFile&#40;LocalFile&#41;;

    qDebug() << "Writing File";
    if (DestFile->open(QFile::Append)) {
        DestFile->write(http->readAll());
        DestFile->flush();
        DestFile->close();
    }

    delete DestFile;
    downloadComplete = true;
    downloadStatus   = SUCCESS;
}

}@

leon.anavi

Depending the user interface of your application you can disable all controls and just set a loading dialog until the download is completed. Btw this is a simple example "how to download data from URL":http://qt-project.org/wiki/Download_Data_from_URL that you might find useful.

Code_ReaQtor

Having the signal-slot implementation early on the contructor class is wrong as it will act as asynchronous. You may use QEventLoop to make things synchrous while making your GUI (for example) responsive.

@http->setHost(Host);
http->get(RemoteFile);
QEventLoop loop;
QObject::connect(reply,SIGNAL(readyRead()),&loop,SLOT(quit()));
loop.exec();
//download here
http->readAll();@

Why dont you use QNetworkAccessManager by the way? QHttp is already obsolete.

From QHttp documentation:

bq. This class is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code.