QT QDateTime

  intmain(intargc,char *argv[])

{

    QApplication a(argc, argv);

    Widget w;

    if(w.m_display)

        w.show();

    else

        QTimer::singleShot(0,qApp,SLOT(quit()));

    return a.exec();

}

void Widget::checkDate()

{

    QFile file("./base.inf");

    QString format("yyyy-MM-dd hh:mm:ss");

    //当前时间

    QDateTime currentTime=QDateTime::currentDateTime();

    QString time=currentTime.toString(format);

    qDebug()<<"currentTime:"<<time;

    //参考时间文件不存在则设置当前时间为参考时间

    if(!file.exists()){

        if(!file.open(QIODevice::WriteOnly))

            qDebug("base.inf open::WriteOnly failed");

        //base64格式存储文本

        QByteArray a=currentTime.toString(format).toUtf8().toBase64();

        file.write(a.data(),a.size());

        file.close();

    }

    if(!file.open(QIODevice::ReadOnly)){

        qDebug("base.inf open::ReadOnly failed");

        m_display=false;

        return;

    }

    //解析base64

    QByteArray timeArray=QByteArray::fromBase64(file.readAll());

    qDebug("baseTime:"+timeArray);

    file.close();

    QDateTime baseTime=QDateTime::fromString(QString(timeArray),format);

    //截止日期设置成参考日期之后一个月

    QDateTime deadLine=baseTime.addMonths(1);

    qDebug()<<"deadLine:"<<deadLine.toString(format);

    //时间天数差值

    int days=currentTime.daysTo(deadLine);

    if(days<0/*currenTime>deadLine*/){

        m_display=false;

        QMessageBox::information(0,"提示","软件试用已结束，请购买正式产品",QMessageBox::Ok);

    }

    else{

        QMessageBox::information(0,"提示",QString("还有%1天试用时间").arg(days),QMessageBox::Ok);

    }

}