downloadmanager.cpp Example File

downloadmanager/downloadmanager.cpp
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#include "downloadmanager.h" #include <QFileInfo> #include <QNetworkRequest> #include <QNetworkReply> #include <QString> #include <QStringList> #include <QTimer> #include <stdio.h> DownloadManager::DownloadManager(QObject *parent) : QObject(parent), downloadedCount(0), totalCount(0) { } void DownloadManager::append(const QStringList &urlList) { foreach (QString url, urlList) append(QUrl::fromEncoded(url.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)) { // already exists, don't overwrite 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; // skip this download } 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())); // prepare the output printf("Downloading %s...\n", url.toEncoded().constData()); downloadTime.start(); } void DownloadManager::downloadProgress(qint64 bytesReceived, qint64 bytesTotal) { progressBar.setStatus(bytesReceived, bytesTotal); // calculate the download speed 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()) { // download failed fprintf(stderr, "Failed: %s\n", qPrintable(currentDownload->errorString())); } else { printf("Succeeded.\n"); ++downloadedCount; } currentDownload->deleteLater(); startNextDownload(); } void DownloadManager::downloadReadyRead() { output.write(currentDownload->readAll()); }