一、写入

    QString fileName = QFileDialog::getSaveFileName(this, "写入", "/untitled.csv", tr("Files (*.csv)"));
    if(fileName.isEmpty())
    {
        QMessageBox::warning(this, "提示", "文件名不能为空", QMessageBox::Ok);
        return;
    }

    QFile file(fileName);
    bool ret = file.open(QIODevice::WriteOnly);
    if(!ret)
    {
        QMessageBox::warning(this, "提示", QString("打开文件失败: %1").arg(file.errorString()), QMessageBox::Ok);
        return;
    }
    QString conTents;
    //表头
    conTents += "姓名";
    conTents += ",";
    conTents += "年龄";
    conTents += ",";
    conTents += "时间";
    conTents += "\n";

    conTents += "张三";
    conTents += ",";
    conTents += "23";
    conTents += ",";
    QString time = QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss.zzz").replace(" ", "-"); //有空格会导致年月日被省略
    conTents += time;
    conTents += "\n";

    conTents += "李四";
    conTents += ",";
    conTents += "24";
    conTents += ",";
    time = QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss.zzz").replace(" ", "-"); //有空格会导致年月日被省略
    conTents += time;
    conTents += "\n";

    conTents += "王五";
    conTents += ",";
    conTents += "25";
    conTents += ",";
    time = QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss.zzz").replace(" ", "-"); //有空格会导致年月日被省略
    conTents += time;
    conTents += "\n";

    QByteArray baSave = QString(conTents).toLocal8Bit(); //格式转换
    file.write(baSave.data());
    file.close();

写入好的文件内容如下：

二、读取

void MainWindow::on_readPushButton_clicked()
{
    QString fileName = QFileDialog::getOpenFileName(this, "读取", "", tr("File (*.csv)"));
    QFile file(fileName);
    if(file.open(QIODevice::ReadOnly)) //只读方式打开文件
    {
        while(!file.atEnd())
        {
            QString strLine = GetCorrectUnicode(file.readLine()); //格式转换
            strLine.remove("\n"); //去掉结尾换行符号
            QStringList strLineList = strLine.split(",");
            if(strLineList.size() > 1)
            {
                qDebug() << strLineList.at(0) << strLineList.at(1) << strLineList.at(2);
            }
        }
        file.close();
    }
}

QString MainWindow::GetCorrectUnicode(const QByteArray &ba)
{
    // state用于保存转换状态，它的成员invalidChars，可用来判断是否转换成功
    // 如果转换成功，则值为0，如果值大于0，则说明转换失败
    QTextCodec::ConverterState state;
    // 先尝试使用utf-8的方式把QByteArray转换成QString
    QString text = QTextCodec::codecForName("UTF-8")->toUnicode(ba.constData(), ba.size(), &state);
    // 如果转换时无效字符数量大于0，说明编码格式不对
    if (state.invalidChars > 0)
    {
        // 再尝试使用GBK的方式进行转换，一般就能转换正确(当然也可能是其它格式，但比较少见了)
        text = QTextCodec::codecForName("GBK")->toUnicode(ba);
    }
    return text;
}

读取的内容如下：