如何更改由Apache Poi生成的图表以不使用平滑线并将空白单元格显示为间隙？

Question

我正在使用POI
3.12-beta1，并且具有在图例中创建具有多个数据集和命名系列的折线图的代码。但是，poi中折线图的默认设置会生成一条已在数据点上平滑的线。空值也被绘制为0，但是我们希望这些行在第一行有一个空单元格处停止。

将其呈现在xlsx文件中后，我可以进入图表属性并更改这些设置，但是我们需要使用这些设置来呈现xlsx。我无法在可用的API中找到任何东西来更改这些设置。

我将此示例类用作我的代码的起点，该代码位于
http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/xssf/usermodel/examples/LineChart
.java

        Drawing drawing = sheet.createDrawingPatriarch();
        ClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 17, 18, 30);
        Chart chart = drawing.createChart(anchor);
        ChartLegend legend = chart.getOrCreateLegend();
        legend.setPosition(LegendPosition.RIGHT);
        LineChartData data = chart.getChartDataFactory().createLineChartData();
        ChartAxis bottomAxis = chart.getChartAxisFactory().createCategoryAxis(AxisPosition.BOTTOM);
        ValueAxis leftAxis = chart.getChartAxisFactory().createValueAxis(AxisPosition.LEFT);
        leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

        int row = 2;
        int startCol = 3;
        int endCol = 17;
        boolean abs = false;
        ChartDataSource<Number> xs = DataSources.fromNumericCellRange(sheet, new CellRangeAddress(row, row, startCol, endCol));

        row = 10;
        int seriesCol = 0;
        ChartDataSource<Number> ys1 = DataSources.fromNumericCellRange(sheet, new CellRangeAddress(row, row, startCol, endCol));
        LineChartSerie ser1 = data.addSerie(xs, ys1);
        ser1.setTitle(new CellReference(sheet.getSheetName(), row, seriesCol, abs, abs));

        row = 11;
        ChartDataSource<Number> ys2 = DataSources.fromNumericCellRange(sheet, new CellRangeAddress(row, row, startCol, endCol));
        LineChartSerie ser2 = data.addSerie(xs, ys2);
        ser2.setTitle(new CellReference(sheet.getSheetName(), row, seriesCol, abs, abs));

        row = 12;
        ChartDataSource<Number> ys3 = DataSources.fromNumericCellRange(sheet, new CellRangeAddress(row, row, startCol, endCol));
        LineChartSerie ser3 = data.addSerie(xs, ys3);
        ser3.setTitle(new CellReference(sheet.getSheetName(), row, seriesCol, abs, abs));

        chart.plot(data, new ChartAxis[] { bottomAxis, leftAxis });

Answer 1

感谢Etienne提供了将空白设置为空白的代码。我从POI开发人员那里得到了帮助，这是解决原始问题中提到的两个问题的解决方案。

    XSSFChart chart = (XSSFChart)drawing.createChart(anchor);

    // this will set blank values as gaps in the chart so you 
    // can accurately plot data series of different lengths
    CTDispBlanksAs disp = CTDispBlanksAs.Factory.newInstance();
    disp.setVal(STDispBlanksAs.GAP);
    chart.getCTChart().setDispBlanksAs(disp);


    // setup chart, axes, data series, etc


    chart.plot(data, new ChartAxis[] { bottomAxis, leftAxis });

    // this must occur after the call to chart.plot above
    CTPlotArea plotArea = chart.getCTChart().getPlotArea();
    for (CTLineChart ch : plotArea.getLineChartList()) {
        for (CTLineSer ser : ch.getSerList()) {
            CTBoolean ctBool = CTBoolean.Factory.newInstance();
            ctBool.setVal(false);
            ser.setSmooth(ctBool);
        }
    }