Download manager : QNetworkAccessManager « Qt « C++

Home
C++
1.Bitset
2.Class
3.Console
4.Data Structure
5.Data Type
6.Deque
7.Development
8.File
9.Function
10.Generic
11.Language
12.List
13.Map Multimap
14.Overload
15.Pointer
16.Qt
17.Queue Stack
18.Set Multiset
19.STL Algorithms Binary search
20.STL Algorithms Heap
21.STL Algorithms Helper
22.STL Algorithms Iterator
23.STL Algorithms Merge
24.STL Algorithms Min Max
25.STL Algorithms Modifying sequence operations
26.STL Algorithms Non modifying sequence operations
27.STL Algorithms Sorting
28.STL Basics
29.String
30.Valarray
31.Vector
C / ANSI-C
C Tutorial
C++ Tutorial
Visual C++ .NET
C++ » Qt » QNetworkAccessManagerScreenshots 
Download manager
  
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial Usage
** Licensees holding valid Qt Commercial licenses may use this file in
** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef TEXTPROGRESSBAR_H
#define TEXTPROGRESSBAR_H

#include <QString>

class TextProgressBar
{
public:
    TextProgressBar();

    void clear();
    void update();
    void setMessage(const QString &message);
    void setStatus(qint64 value, qint64 maximum);

private:
    QString message;
    qint64 value;
    qint64 maximum;
    int iteration;
};

#endif






#include "textprogressbar.h"
#include <QByteArray>
#include <stdio.h>

TextProgressBar::TextProgressBar()
    : value(0), maximum(-1), iteration(0)
{
}

void TextProgressBar::clear()
{
    printf("\n");
    fflush(stdout);

    iteration = 0;
    value = 0;
    maximum = -1;
}

void TextProgressBar::update()
{
    ++iteration;

    if (maximum > 0) {
        // we know the maximum
        // draw a progress bar
        int percent = value * 100 / maximum;
        int hashes = percent / 2;

        QByteArray progressbar(hashes, '#');
        if (percent % 2)
            progressbar += '>';

        printf("\r[%-50s] %3d%% %s     ",
               progressbar.constData(),
               percent,
               qPrintable(message));
    else {
        // we don't know the maximum, so we can't draw a progress bar
        int center = (iteration % 481// 50 spaces, minus 2
        QByteArray before(qMax(center - 20)' ');
        QByteArray after(qMin(center + 250)' ');

        printf("\r[%s###%s]      %s      ",
               before.constData(), after.constData(), qPrintable(message));
    }
}

void TextProgressBar::setMessage(const QString &m)
{
    message = m;
}

void TextProgressBar::setStatus(qint64 val, qint64 max)
{
    value = val;
    maximum = max;
}






#ifndef DOWNLOADMANAGER_H
#define DOWNLOADMANAGER_H

#include <QFile>
#include <QObject>
#include <QQueue>
#include <QTime>
#include <QUrl>
#include <QNetworkAccessManager>

#include "textprogressbar.h"

class DownloadManager: public QObject
{
    Q_OBJECT
public:
    DownloadManager(QObject *parent = 0);

    void append(const QUrl &url);
    void append(const QStringList &urlList);
    QString saveFileName(const QUrl &url);

signals:
    void finished();

private slots:
    void startNextDownload();
    void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
    void downloadFinished();
    void downloadReadyRead();

private:
    QNetworkAccessManager manager;
    QQueue<QUrl> downloadQueue;
    QNetworkReply *currentDownload;
    QFile output;
    QTime downloadTime;
    TextProgressBar progressBar;

    int downloadedCount;
    int totalCount;
};

#endif





#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());
}






#include <QCoreApplication>
#include <QStringList>
#include "downloadmanager.h"
#include <stdio.h>

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    QStringList arguments = app.arguments();
    arguments.takeFirst();      // remove the first argument, which is the program's name

    if (arguments.isEmpty()) {
        printf("Qt Download example\n"
               "Usage: downloadmanager url1 [url2... urlN]\n"
               "\n"
               "Downloads the URLs passed in the command-line to the local directory\n"
               "If the target file already exists, a .0, .1, .2, etc. is appended to\n"
               "differentiate.\n");
        return 0;
    }

    DownloadManager manager;
    manager.append(arguments);

    QObject::connect(&manager, SIGNAL(finished()), &app, SLOT(quit()));
    app.exec();
}

   
    
  
Related examples in the same category
1.Download from URL
2.QNetworkAccessManager based google suggest
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.