POI 5.2.2版本中添加次要坐标轴的代码示例

在POI 5.2.2版本中，没有直接提供添加次要坐标轴的方法。次要坐标轴是一种在图表中显示多个不同范围的坐标轴的方式，可以用来展示不同单位或不同数据类型的数据。

要实现次要坐标轴，可以使用POI的底层库Apache poi-ooxml-schemas来创建自定义的图表XML，并将其插入到Excel文件中。以下是一个添加次要坐标轴的示例代码：

import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.xssf.usermodel.charts.*;
import org.openxmlformats.schemas.drawingml.x2006.chart.*;

import java.io.FileOutputStream;

public class SecondaryAxisExample {
    public static void main(String[] args) throws Exception {
        try (XSSFWorkbook workbook = new XSSFWorkbook()) {
            XSSFSheet sheet = workbook.createSheet("Chart");

            // Create a sample dataset
            XSSFRow row;
            XSSFCell cell;
            for (int i = 0; i < 10; i++) {
                row = sheet.createRow(i);
                cell = row.createCell(0);
                cell.setCellValue(i);

                cell = row.createCell(1);
                cell.setCellValue(i * 10);
            }

            // Create a chart
            XSSFDrawing drawing = sheet.createDrawingPatriarch();
            XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 4, 2, 12, 15);
            XSSFChart chart = drawing.createChart(anchor);

            // Create chart axis
            XDDFChartAxis bottomAxis = chart.createCategoryAxis(AxisPosition.BOTTOM);
            XDDFValueAxis leftAxis = chart.createValueAxis(AxisPosition.LEFT);
            XDDFValueAxis rightAxis = chart.createValueAxis(AxisPosition.RIGHT);

            // Set the axis cross between
            leftAxis.crossAxis(rightAxis);
            rightAxis.crossAxis(leftAxis);

            // Set the axis position
            leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);
            rightAxis.setCrosses(AxisCrosses.MAX);

            // Create chart data sources
            XDDFDataSource<Double> leftAxisDataSource = XDDFDataSourcesFactory.fromNumericCellRange(sheet, new CellRangeAddress(0, 9, 0, 0));
            XDDFDataSource<Double> rightAxisDataSource = XDDFDataSourcesFactory.fromNumericCellRange(sheet, new CellRangeAddress(0, 9, 1, 1));

            // Create left axis plot
            XDDFLineChartData leftAxisData = (XDDFLineChartData) chart.createData(ChartTypes.LINE, bottomAxis, leftAxis);
            XDDFLineChartData.Series leftAxisSeries = (XDDFLineChartData.Series) leftAxisData.addSeries(leftAxisDataSource, null);
            leftAxisSeries.setTitle('Left Axis', null);

            // Create right axis plot
            XDDFLineChartData rightAxisData = (XDDFLineChartData) chart.createData(ChartTypes.LINE, bottomAxis, rightAxis);
            XDDFLineChartData.Series rightAxisSeries = (XDDFLineChartData.Series) rightAxisData.addSeries(rightAxisDataSource, null);
            rightAxisSeries.setTitle('Right Axis', null);

            // Combine left and right axis plots
            leftAxisData.combine(rightAxisData);

            // Plot the chart
            chart.plot(leftAxisData);

            // Save the workbook
            try (FileOutputStream fileOut = new FileOutputStream("chart_with_secondary_axis.xlsx")) {
                workbook.write(fileOut);
            }
        }
    }
}

这个示例代码创建了一个包含两列数据的Excel表格，并在图表中展示了这两列数据。左侧的坐标轴显示第一列数据，右侧的坐标轴显示第二列数据。