poi导出柱状图

要在POI中导出柱状图，您需要使用Apache POI的XSSF图表类。以下是一个简单的示例代码，可以用于创建一个简单的柱状图并将其导出到Excel文件中：

import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.*;
import org.apache.poi.xssf.usermodel.*;

public class BarChartExample {
    public static void main(String[] args) throws Exception {

        // Create a Workbook
        XSSFWorkbook workbook = new XSSFWorkbook();

        // Create a Sheet
        XSSFSheet sheet = workbook.createSheet("Bar Chart");

        // Create some data for the chart
        Object[][] data = {
                {"Category", "Value"},
                {"A", 10},
                {"B", 20},
                {"C", 30},
                {"D", 40},
                {"E", 50}
        };

        // Create a Chart
        XSSFDrawing drawing = sheet.createDrawingPatriarch();
        XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 5, 10, 15);
        XSSFChart chart = drawing.createChart(anchor);

        // Define the chart data source
        XSSFDrawing drawing2 = chart.getSheet().createDrawingPatriarch();
        XSSFChartLegend legend = chart.getOrCreateLegend();
        XSSFChartAxis bottomAxis = chart.getChartAxisFactory().createCategoryAxis(AxisPosition.BOTTOM);
        XSSFValueAxis leftAxis = chart.getChartAxisFactory().createValueAxis(AxisPosition.LEFT);
        leftAxis.setCrosses(AxisCrosses.AUTO_ZERO);

        XSSFChartData dataChart = chart.getChartDataFactory().createBarChart(
                DataSources.fromArray(data),
                bottomAxis,
                leftAxis
        );
        dataChart.setBarGrouping(BarGrouping.CLUSTERED);

        // Output the Workbook to a file
        FileOutputStream fileOut = new FileOutputStream("BarChartExample.xlsx");
        workbook.write(fileOut);
        fileOut.close();

        // Close the Workbook
        workbook.close();
    }
}

这个示例代码创建了一个包含柱状图的Excel文件，该图表显示了一些简单的数据。您可以根据需要更改数据源和图表类型。