1、引入pom依赖

        <!--icepdf，用来将pdf文件转换为图片的依赖-->
        <dependency>
            <groupId>org.icepdf.os</groupId>
            <artifactId>icepdf-core</artifactId>
            <version>6.2.2</version>

            <exclusions>
                <exclusion>
                    <groupId>javax.media</groupId>
                    <artifactId>jai_core</artifactId>
                </exclusion>
            </exclusions>

        </dependency>

2、测试代码

    @Test
    void testSavePdf() throws InterruptedException {
        String filePath = "E:\\david\\在线教育.pdf";
        Document document = new Document();
        try {
            document.setFile(filePath);
        } catch (Exception ex) {
        }

        // save page caputres to file.
        float scale = 2f;
        float rotation = 0f;

        // Paint each pages content to an image and write the image to fil
        for (int i = 0; i < document.getNumberOfPages(); i++) {
            BufferedImage image = (BufferedImage)document.getPageImage(i, GraphicsRenderingHints.SCREEN,
                    Page.BOUNDARY_CROPBOX, rotation, scale);
            RenderedImage rendImage = image;

            // capture the page image to file
            try {
                System.out.println("/t capturing page " + i);
                File file = new File("E:\\var\\tmp\\image_" + i + ".png");
                ImageIO.write(rendImage, "png", file);
            } catch (IOException e) {
                e.printStackTrace();
            }
            image.flush();
        }

        // clean up resources
        document.dispose();
    }