主要代码如下：

void Widget::InitQLineXDateAddData()
{
    customPlot = new QCustomPlot(this);

    // 创建日期时间类型的刻度生成器
    QSharedPointer<QCPAxisTickerDateTime> dateTimeTicker(new QCPAxisTickerDateTime);
    dateTimeTicker->setDateTimeFormat("yyyy-MM-dd"); // 设置日期时间格式
    //dateTimeTicker->setTickCount(8);
    // 将刻度生成器应用到 X 轴
    customPlot->xAxis->setTicker(dateTimeTicker);
    customPlot->xAxis->setTickLabelRotation(45); // 设置刻度标签旋转角度，以便更好地显示

    // 设置 X 轴的范围（使用 QDateTime 转换为键）
    QDateTime startDateTime = QDateTime(QDate(2024, 3, 13), QTime(0, 0, 0), Qt::UTC);
    QDateTime endDateTime = QDateTime(QDate(2024, 3, 20), QTime(0, 0, 0), Qt::UTC); 
    // 计算日期范围内的天数，并设置为刻度数量
   int numDays = startDateTime.daysTo(endDateTime) + 1; // 包括开始和结束日期
   dateTimeTicker->setTickCount(numDays);

    // 将 QDateTime 转换为自 Unix 纪元以来的秒数
    double startKey = startDateTime.toMSecsSinceEpoch() / 1000.0;
    double endKey = endDateTime.toMSecsSinceEpoch() / 1000.0;
    customPlot->xAxis->setRange(QCPRange(startKey, endKey));


    // 添加并设置两个图形的pen
    QCPGraph *graph1 = customPlot->addGraph();
    graph1->setPen(QPen(Qt::blue));
    QCPGraph *graph2 = customPlot->addGraph();
    graph2->setPen(QPen(Qt::red));


    // 设置图例
    customPlot->legend->setVisible(true);
    graph1->setName("A产品");
    graph2->setName("B产品");
    customPlot->axisRect()->insetLayout()->setInsetAlignment(0,Qt::AlignBottom|Qt::AlignRight);
    graph1->setLineStyle(QCPGraph::lsLine); // 实线
    graph1->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDisc, QColor(Qt::blue), 6)); // 圆形散点

    graph2->setLineStyle(QCPGraph::lsLine); // 实线
    graph2->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDisc, 6)); // 圆形散点

    QVector<double> keys1;
    int numValues = 6; // 要生成的值的数量

    for (int i = 0; i < numValues; ++i ) {
        keys1.push_back(startKey + i * 86400);
    }
    QVector<double> values1 = {100, 300, 500, 800, 900, 800};


    QVector<double> keys2 = {startKey, startKey + 86400, startKey + 2 * 86400, startKey + 3 * 86400, startKey + 4 * 86400, startKey + 5 * 86400};
    QVector<double> values2 = {100, 200, 400, 900, 1100, 600};

    // 设置数据并显示图表
    graph1->setData(keys1, values1);
    graph2->setData(keys2, values2);

    // 设置数据点标签显示
    for (int i = 0; i < keys1.size(); ++i) {
        QCPItemText *textItem = new QCPItemText(customPlot);
        //textItem->setPositionAlignment(Qt::AlignTop | Qt::AlignHCenter);

        textItem->setPositionAlignment( Qt::AlignBottom | Qt::AlignHCenter);

        textItem->position->setType(QCPItemPosition::ptPlotCoords);
        textItem->position->setCoords(keys1[i], values1[i]);
        textItem->setText(QString::number(values1[i]));
        textItem->setFont(QFont(font().family(), 10)); // Set font size as needed
        //textItem->setPen(QPen(Qt::blue)); // Set text color

        textItem->setPen(Qt::NoPen); // Set no pen (remove border)
        textItem->setBrush(QBrush(Qt::transparent)); // Set transparent brush to hide the background

    }


    // 设置数据点标签显示
    for (int i = 0; i < keys1.size(); ++i) {
        QCPItemText *textItem = new QCPItemText(customPlot);
        //textItem->setPositionAlignment(Qt::AlignTop | Qt::AlignHCenter);

        textItem->setPositionAlignment( Qt::AlignBottom | Qt::AlignHCenter);

        textItem->position->setType(QCPItemPosition::ptPlotCoords);
        textItem->position->setCoords(keys1[i], values2[i]);
        textItem->setText(QString::number(values2[i]));
        textItem->setFont(QFont(font().family(), 10)); // Set font size as needed
        //textItem->setPen(QPen(Qt::blue)); // Set text color

        textItem->setPen(Qt::NoPen); // Set no pen (remove border)
        textItem->setBrush(QBrush(Qt::transparent)); // Set transparent brush to hide the background

    }


    // 整个折线图标题
    QCPTextElement* PlotTitle = new QCPTextElement(customPlot, "折线图统计分析-近5天对比");
    //PlotTitle->setPositionAlignment(Qt::AlignCenter);

    PlotTitle->setFont(QFont("宋体", 12, QFont::Bold)); // 设置标题的字体


    customPlot->plotLayout()->insertRow(0); // 在图表布局中插入一行
    customPlot->plotLayout()->addElement(0, 0, PlotTitle); // 将标题添加到插入的行


    // 设置Y轴范围为0-2000
    customPlot->yAxis->setRange(0, 2000);
    customPlot->yAxis->ticker()->setTickCount(10);

    customPlot->setGeometry(QRect(10,20,700,600));


    // 自动调整坐标轴范围以适应数据，并重新绘制图表
    //customPlot->rescaleAxes();
    customPlot->replot();


    QVBoxLayout* pVBoxLayout = new QVBoxLayout(this);
    pVBoxLayout->addWidget(customPlot);

}