C++/Qt/QDataStream

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Create QDataStream from QBuffer

  
/****************************************************************************
**
** 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 documentation 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.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QApplication>
#include <QBuffer>
#include <QPalette>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QByteArray byteArray;
    QBuffer buffer(&byteArray);
    buffer.open(QIODevice::WriteOnly);
    QDataStream out(&buffer);
    out << QApplication::palette();
    return 0;
}


Read datastream

  
/****************************************************************************
**
** 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 documentation 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.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QApplication>
#include <QBuffer>
#include <QPalette>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QByteArray byteArray;

    QPalette palette;
    QBuffer buffer(&byteArray);
    buffer.open(QIODevice::ReadOnly);
    QDataStream in(&buffer);
    in >> palette;
    return 0;
}


Saving file with QDataStream

  

Foundations of Qt Development\Chapter08\datastream\main.cpp
/*
 * Copyright (c) 2006-2007, Johan Thelin
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 * 
 *     * Redistributions of source code must retain the above copyright notice, 
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright notice,  
 *       this list of conditions and the following disclaimer in the documentation 
 *       and/or other materials provided with the distribution.
 *     * Neither the name of APress nor the names of its contributors 
 *       may be used to endorse or promote products derived from this software 
 *       without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */
#include <QFile>
#include <QDataStream>
#include <QList>
#include <QColor>
#include <QtDebug>
struct ColorText
{
  QString text;
  QColor color;
};
QDataStream &operator<<( QDataStream &stream, const ColorText &data )
{
  stream << data.text << data.color;
  
  return stream;
}
QDataStream &operator>>( QDataStream &stream, ColorText &data )
{
  stream >> data.text;
  stream >> data.color;
  
  return stream;
}
void saveList()
{
  QList<ColorText> list;
  ColorText data;
  
  data.text = "Red";
  data.color = Qt::red;
  list << data;
  
  data.text = "Blue";
  data.color = Qt::blue;
  list << data;
  data.text = "Yellow";
  data.color = Qt::yellow;
  list << data;
  data.text = "Green";
  data.color = Qt::green;
  list << data;
  
  QFile file( "test.dat" );
  if( !file.open( QIODevice::WriteOnly ) )
    return;
    
  QDataStream stream( &file );
  stream.setVersion( QDataStream::Qt_4_2 );
  
  stream << list;
  
  file.close();
}
void loadList()
{
  QList<ColorText> list;
  
  QFile file( "test.dat" );
  if( !file.open( QIODevice::ReadOnly ) )
    return;
    
  QDataStream stream( &file );
  stream.setVersion( QDataStream::Qt_4_2 );
  stream >> list;
  
  file.close();
  foreach( ColorText data, list )
    qDebug() << data.text << "(" 
             << data.color.red() << "," 
             << data.color.green() << "," 
             << data.color.blue() << ")";
}
int main( int argc, char **argv )
{
  saveList();
  loadList();
  
  return 0;
}


Serialization with QDataStream

  

/****************************************************************************
**
** 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 documentation 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.
** $QT_END_LICENSE$
**
****************************************************************************/
#include <QtGui>
#include <QByteArray>
#include <QDataStream>

struct Movie
{
    int id;
    QString title;
    QDate releaseDate;
};

QDataStream &operator<<(QDataStream &out, const Movie &movie)
{
    out << (quint32)movie.id << movie.title
        << movie.releaseDate;
    return out;
}

QDataStream &operator>>(QDataStream &in, Movie &movie)
{
    quint32 id;
    QDate date;
    in >> id >> movie.title >> date;
    movie.id = (int)id;
    movie.releaseDate = date;
    return in;
}

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Movie m;
    m.id = 0001;
    m.title = "Happy Meal";
    m.releaseDate = QDate(1995, 5, 17);
    QByteArray byteArray;
    QDataStream stream(&byteArray, QIODevice::WriteOnly);
    stream << m;
    
    // display
    qDebug() << m.id << m.releaseDate << m.title;
    Movie m2;
    
    int id2;
    QString title2;
    QDate date2;
    QDataStream stream2(byteArray);
    stream2 >> id2 >> title2 >> date2;
    m2.id = id2;
    m2.title = title2;
    m2.releaseDate = date2;
    qDebug() << id2 << " " << date2 << " " << title2;
    return 0;
}