根据使用Apache POI的数据对BarChart条进行着色

// 创建工作簿
Workbook workbook = new XSSFWorkbook();

// 创建工作表
Sheet sheet = workbook.createSheet("BarChart");

// 创建数据
Row row = sheet.createRow(0);
row.createCell(0).setCellValue("Category");
row.createCell(1).setCellValue("Value");

row = sheet.createRow(1);
row.createCell(0).setCellValue("Category 1");
row.createCell(1).setCellValue(10);

row = sheet.createRow(2);
row.createCell(0).setCellValue("Category 2");
row.createCell(1).setCellValue(20);

// 创建BarChart
Drawing<?> drawing = sheet.createDrawingPatriarch();
ClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 4, 10, 20);
Chart chart = drawing.createChart(anchor);
ChartLegend legend = chart.getOrCreateLegend();
legend.setPosition(LegendPosition.BOTTOM);

BarChartData data = new BarChartDataBuilder()
        .setCategories(CellRangeAddress.valueOf("A2:A3"))
        .addSeries(CellRangeAddress.valueOf("B2:B3"), DataSources.fromNumericCellRange(sheet, CellRangeAddress.valueOf("B2:B3")))
        .build();

chart.plot(data);

// 获取BarChart的绘图区域
ChartPlotArea plotArea = chart.getOrCreatePlotArea();

// 获取BarChart的系列
List<Series> seriesList = plotArea.getSeries();

// 设置第一个条的颜色为红色
Series firstSeries = seriesList.get(0);
firstSeries.setFillForegroundColor(IndexedColors.RED.getIndex());

// 设置第二个条的颜色为蓝色
Series secondSeries = seriesList.get(1);
secondSeries.setFillForegroundColor(IndexedColors.BLUE.getIndex());

// 保存Excel文档到文件
FileOutputStream fileOut = new FileOutputStream("bar_chart.xlsx");
workbook.write(fileOut);
fileOut.close();

// 或者将Excel文档输出到输出流
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
workbook.write(outputStream);