一起看代码来玩玩QT之13 IO(one 基本)

#ifndef MYWIDGET_H
#define MYWIDGET_H

#include <QWidget>

class MyWidget : public QWidget
{
Q_OBJECT
public:
explicit MyWidget(QWidget *parent = 0);

signals:

public slots:

};

#endif // MYWIDGET_H

#include "MyWidget.h"
#include <QFile>
#include <QApplication>
#include <QDebug>
#include <QBuffer>
#include <QLabel>
#include <QTextStream>
#include <QDataStream>

/*
QFile
QBuffer // memory file
QTcpSocket
QUdpSocket

QDataStream  // io method
QTextStream
*/

MyWidget::MyWidget(QWidget *parent) :
QWidget(parent)
{
#if 0
QFile file("../MyTest.txt");
file.open(QIODevice::ReadWrite);

file.write(QByteArray("abc"));
// file.seek
// file.write()

file.close();
#endif

#if 0
QBuffer buffer;
buffer.open(QIODevice::ReadWrite);

buffer.write("abc");
buffer.write("aabbcc");

buffer.close();

qDebug() << buffer.buffer();
#endif

#if 0
// send side
QBuffer buffer;
buffer.open(QIODevice::ReadWrite);
QPixmap pixmap("../aaa.png");
pixmap.save(&buffer, "PNG");
buffer.close();

qDebug() << buffer.buffer().size();

// recv side
QPixmap pixmap2;
pixmap2.loadFromData(buffer.buffer(), "PNG");

QLabel* label = new QLabel(this);
label->setPixmap(pixmap2);
#endif

#if 0
QByteArray ba("哈哈");
QString str("哈哈");

qDebug() << ba.size() << str.size();
#endif

#if 0
QFile file("../teststream.txt");
file.open(QIODevice::ReadWrite);

QTextStream textStream(&file);

textStream << 1 << "abc" << 1.2 << QString("abc");

file.close();
#endif
#if 0
QFile file("../datastream.txt");
file.open(QIODevice::ReadWrite);

QDataStream dataStream(&file);

dataStream << 1 << "abc" << 1.2 << QString("abc") << QPoint(1, 1);

file.close();
#endif

#if 0
QFile file("../datastream.txt");
file.open(QIODevice::ReadWrite);

QDataStream dataStream(&file);

int i;
char* buf;
double d;
QString str;
QPoint pt;

dataStream >> i >> buf >> d >> str >> pt;

delete[] buf;

qDebug() << i << buf << d << str << pt;
file.close();

#endif

#if 0
// virtual memory
QFile file("../map.txt");

file.open(QIODevice::ReadWrite);
file.seek(65535);
file.write("1");
file.close();
file.open(QIODevice::ReadWrite);

uchar* ptr = file.map(0, 64*1024);

// write file
*ptr = 'a';
ptr[1] = 'b';

// read file
uchar ch = *ptr;

file.unmap(ptr);
file.close();
#endif
}

int main(int argc, char** argv)
{
QApplication app(argc, argv);

MyWidget w;
w.show();

return app.exec();
}