1.引入maven依赖

        <dependency>
            <groupId>org.jfree</groupId>
            <artifactId>jfreechart</artifactId>
            <version>1.5.3</version>
        </dependency>
        <dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>itextpdf</artifactId>
            <version>5.5.13</version>
        </dependency>

2.java代码示例

package com.github.xiaoymin.knife4j.spring.util;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtils;
import org.jfree.chart.JFreeChart;
import org.jfree.data.category.DefaultCategoryDataset;
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.pdf.PdfWriter;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class ChartToPDF {

    public static void main(String[] args) {
        // 创建一个数据集
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.addValue(1, "Category 1", "Value 1");
        dataset.addValue(2, "Category 1", "Value 2");
        dataset.addValue(3, "Category 2", "Value 1");
        dataset.addValue(4, "Category 2", "Value 2");

        // 创建图表
        JFreeChart chart = ChartFactory.createBarChart("Bar Chart", "Category", "Value", dataset);

        // 保存图表为PNG文件
        try {
            ChartUtils.saveChartAsPNG(new File("barchart.png"), chart, 400, 300);
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 将图表保存为PDF文件
        Document document = new Document();
        try {
            PdfWriter.getInstance(document, new FileOutputStream("barchart.pdf"));
            document.open();
            com.itextpdf.text.Image image = com.itextpdf.text.Image.getInstance("barchart.png");
            document.add(image);
            document.close();
        } catch (DocumentException | IOException e) {
            e.printStackTrace();
        }
    }
}

3.实现效果