QIODevice概述

Qt 中所有IO 设备的基类是QIODevice,派生出来的子类有以下几种
1.QFile：磁盘文件，存储在磁盘中的文件
2.QBuffer ：内存文件，存储在内存中
3.QTcpSocket
4.QUdpSocket
//io method
1.QTextStream
2.QDataStream

#if 0
    QFile file("C:\\Users\\michael\\Desktop\\1.txt");
    file.open(QIODevice::ReadWrite);

    file.write(QByteArray("yzh"));
    file.write(QByteArray("yzh"));
    file.close();
    QByteArray ba("中国人");
    QString str("是什么意思");
    qDebug()<<ba.size()<<endl<<str.size()<<endl;
#endif
#if 0
    QBuffer  buf;
    buf.open(QIODevice::ReadWrite);
    buf.write("0901");
    buf.close();
    qDebug()<<buf.buffer();
#endif

    //内存文件应用
#if 1
    //send side
    QBuffer  buf;
    buf.open(QIODevice::ReadWrite);
    QPixmap pix("C:\\Users\\michael\\Desktop\\green.png");
//    pix.save("C:\\Users\\michael\\Desktop\\greenball.png");//以文件名方式另存为
    pix.save(&buf,"PNG");//图片保存在内存文件中,效率更高,可使用网络进行传输.
    qDebug()<<buf.buffer().size();

    // recv side
    QPixmap recvPix;
    recvPix.loadFromData(buf.buffer(), "PNG");
    QLabel* label = new QLabel(this);
    label->setPixmap(recvPix);
#endif
  //QTextStream 调试用,解析时候比较麻烦,数据类型太杂
#if 0
    QFile file("../textstream.txt");
    file.open(QIODevice::ReadWrite);

    QTextStream textStream(&file);

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

    file.close();
#endif
//方便读写,文件解析
#if 1
    QFile file("../datastream.txt");
    file.open(QIODevice::ReadWrite);

    QDataStream wDataStream(&file);

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

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

    QFile rFile("../datastream.txt");
    rFile.open(QIODevice::ReadWrite);
    QDataStream rDataStream(&rFile);

    rDataStream >> i >> buffer >> d >> str >> pt;
    qDebug() << i << buffer << d << str << pt;
    delete []buffer;

    file.close();
#endif
    this->setFixedSize(200,200);