downloadmanager.cpp Example File
downloadmanager/downloadmanager.cpp
#include "downloadmanager.h"
#include <QTextStream>
#include <cstdio>
using namespace std;
DownloadManager::DownloadManager(QObject *parent)
: QObject(parent)
{
}
void DownloadManager::append(const QStringList &urls)
{
for (const QString &urlAsString : urls)
append(QUrl::fromEncoded(urlAsString.toLocal8Bit()));
if (downloadQueue.isEmpty())
QTimer::singleShot(0, this, SIGNAL(finished()));
}
void DownloadManager::append(const QUrl &url)
{
if (downloadQueue.isEmpty())
QTimer::singleShot(0, this, SLOT(startNextDownload()));
downloadQueue.enqueue(url);
++totalCount;
}
QString DownloadManager::saveFileName(const QUrl &url)
{
QString path = url.path();
QString basename = QFileInfo(path).fileName();
if (basename.isEmpty())
basename = "download";
if (QFile::exists(basename)) {
int i = 0;
basename += '.';
while (QFile::exists(basename + QString::number(i)))
++i;
basename += QString::number(i);
}
return basename;
}
void DownloadManager::startNextDownload()
{
if (downloadQueue.isEmpty()) {
printf("%d/%d files downloaded successfully\n", downloadedCount, totalCount);
emit finished();
return;
}
QUrl url = downloadQueue.dequeue();
QString filename = saveFileName(url);
output.setFileName(filename);
if (!output.open(QIODevice::WriteOnly)) {
fprintf(stderr, "Problem opening save file '%s' for download '%s': %s\n",
qPrintable(filename), url.toEncoded().constData(),
qPrintable(output.errorString()));
startNextDownload();
return;
}
QNetworkRequest request(url);
currentDownload = manager.get(request);
connect(currentDownload, SIGNAL(downloadProgress(qint64,qint64)),
SLOT(downloadProgress(qint64,qint64)));
connect(currentDownload, SIGNAL(finished()),
SLOT(downloadFinished()));
connect(currentDownload, SIGNAL(readyRead()),
SLOT(downloadReadyRead()));
printf("Downloading %s...\n", url.toEncoded().constData());
downloadTime.start();
}
void DownloadManager::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
{
progressBar.setStatus(bytesReceived, bytesTotal);
double speed = bytesReceived * 1000.0 / downloadTime.elapsed();
QString unit;
if (speed < 1024) {
unit = "bytes/sec";
} else if (speed < 1024*1024) {
speed /= 1024;
unit = "kB/s";
} else {
speed /= 1024*1024;
unit = "MB/s";
}
progressBar.setMessage(QString::fromLatin1("%1 %2")
.arg(speed, 3, 'f', 1).arg(unit));
progressBar.update();
}
void DownloadManager::downloadFinished()
{
progressBar.clear();
output.close();
if (currentDownload->error()) {
fprintf(stderr, "Failed: %s\n", qPrintable(currentDownload->errorString()));
output.remove();
} else {
if (isHttpRedirect()) {
reportRedirect();
output.remove();
} else {
printf("Succeeded.\n");
++downloadedCount;
}
}
currentDownload->deleteLater();
startNextDownload();
}
void DownloadManager::downloadReadyRead()
{
output.write(currentDownload->readAll());
}
bool DownloadManager::isHttpRedirect() const
{
int statusCode = currentDownload->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
return statusCode == 301 || statusCode == 302 || statusCode == 303
|| statusCode == 305 || statusCode == 307 || statusCode == 308;
}
void DownloadManager::reportRedirect()
{
int statusCode = currentDownload->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
QUrl requestUrl = currentDownload->request().url();
QTextStream(stderr) << "Request: " << requestUrl.toDisplayString()
<< " was redirected with code: " << statusCode
<< '\n';
QVariant target = currentDownload->attribute(QNetworkRequest::RedirectionTargetAttribute);
if (!target.isValid())
return;
QUrl redirectUrl = target.toUrl();
if (redirectUrl.isRelative())
redirectUrl = requestUrl.resolved(redirectUrl);
QTextStream(stderr) << "Redirected to: " << redirectUrl.toDisplayString()
<< '\n';
}