java依据数据源生成柱状图并放在excel中

要在Java中生成柱状图并将其放在Excel中，可以使用Apache POI和JFreeChart库。

步骤如下：

1.导入POI和JFreeChart库

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.data.category.*;

2.创建Excel工作簿和工作表

XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet sheet = workbook.createSheet("Bar Chart");

3.创建数据源并添加数据

DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.setValue(50, "", "Apples");
dataset.setValue(80, "", "Bananas");
dataset.setValue(120, "", "Oranges");

4.创建柱状图并设置样式

JFreeChart barChart = ChartFactory.createBarChart(
        "Fruit Sales", // 标题
        "", // x轴标签
        "Sales", // y轴标签
        dataset, // 数据集
        PlotOrientation.VERTICAL, // 图表方向
        false, // 是否显示图例
        true, // 是否显示工具提示
        false // 是否生成URL链接
);
CategoryPlot plot = barChart.getCategoryPlot();
plot.setRangeGridlinePaint(Color.BLACK); // 设置水平网格线颜色

5.将图表插入Excel中

ByteArrayOutputStream chartOut = new ByteArrayOutputStream();
ChartUtilities.writeChartAsPNG(chartOut, barChart, 500, 300);
int chartIndex = workbook.addPicture(chartOut.toByteArray(), Workbook.PICTURE_TYPE_PNG);
XSSFDrawing drawing = sheet.createDrawingPatriarch();
XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 5, 8, 20);
drawing.createPicture(anchor, chartIndex);

完整代码示例：

import java.io.*;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.*;
import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.data.category.*;

public class BarChartExample {

    public static void main(String[] args) throws IOException {
        XSSFWorkbook workbook = new XSSFWorkbook();
        XSSFSheet sheet = workbook.createSheet("Bar Chart");

        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.setValue(50, "", "Apples");
        dataset.setValue(80, "", "Bananas");
        dataset.setValue(120, "", "Oranges");

        JFreeChart barChart = ChartFactory.createBarChart(
                "Fruit Sales",
                "",
                "Sales",
                dataset,
                PlotOrientation.VERTICAL,
                false,
                true,
                false
        );
        CategoryPlot plot = barChart.getCategoryPlot();
        plot.setRangeGridlinePaint(Color.BLACK);

        ByteArrayOutputStream chartOut = new ByteArrayOutputStream();
        ChartUtilities.writeChartAsPNG(chartOut, barChart, 500, 300);
        int chartIndex = workbook.addPicture(chartOut.toByteArray(), Workbook.PICTURE_TYPE_PNG);
        XSSFDrawing drawing = sheet.createDrawingPatriarch();
        XSSFClientAnchor anchor = drawing.createAnchor(0, 0, 0, 0, 0, 5, 8, 20);
        drawing.createPicture(anchor, chartIndex);

        FileOutputStream fileOut = new FileOutputStream("BarChart.xlsx");
        workbook.write(fileOut);
        fileOut.close();
        workbook.close();
    }
}