1、主要有时间戳->QDateTime,QDateTime->QString

2、同时QString->QDateTime,QDateTime->时间戳

详情见代码：

    //QDateTime转时间戳
    qint64 time = QDateTime::currentSecsSinceEpoch();

    double nowTime = (double)time;
    qDebug()<<"nowTime1111=="<<nowTime;

    //时间戳转QDateTime,QDateTime转QString
    QString strTime = QDateTime::fromSecsSinceEpoch(time).toString("yyyy-MM-dd hh:mm:ss");

    qDebug()<<"strTime11111==="<<strTime;

    qDebug()<<"=======================================";

    //QString转QDateTime
    QDateTime dateTime = QDateTime::fromString(strTime, "yyyy-MM-dd hh:mm:ss");

    //QDateTime又转时间戳
    qint64 timeTemp = dateTime.toSecsSinceEpoch();

    double nowTime2 = (double)timeTemp;

    qDebug()<<"nowTime2222=="<<nowTime2;
    QString strTime2 = QDateTime::fromSecsSinceEpoch(timeTemp).toString("yyyy-MM-dd hh:mm:ss");

    qDebug()<<"strTime222222==="<<strTime2;