C++/Qt/QDataStream

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Create QDataStream from QBuffer

<source lang="cpp"> /****************************************************************************

    • 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.
    • $QT_END_LICENSE$
                                                                                                                                                        • /
  1. include <QApplication>
  2. include <QBuffer>
  3. 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;

} 


 </source>


Read datastream

<source lang="cpp"> /****************************************************************************

    • 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.
    • $QT_END_LICENSE$
                                                                                                                                                        • /
  1. include <QApplication>
  2. include <QBuffer>
  3. 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;

} 


 </source>


Saving file with QDataStream

<source lang="cpp">

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.
*
*/
  1. include <QFile>
  2. include <QDataStream>
  3. include <QList>
  4. include <QColor>
  5. 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;

} 


 </source>


Serialization with QDataStream

<source lang="cpp">

/****************************************************************************

    • 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.
    • $QT_END_LICENSE$
                                                                                                                                                        • /
  1. include <QtGui>
  2. include <QByteArray>
  3. 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;

} 


 </source>
Источник — «http://cppe.ru/index.php?title=C%2B%2B/Qt/QDataStream&oldid=1085»