Java pdf转图片

        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.28</version>
        </dependency>
        <dependency>
    		<groupId>cn.hutool</groupId>
  		    <artifactId>hutool-all</artifactId>
 		    <version>5.8.16</version>
		</dependency>

import cn.hutool.core.util.ObjectUtil;
import cn.hutool.http.HttpUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.ImageType;
import org.apache.pdfbox.rendering.PDFRenderer;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.Base64;
import java.util.List;
import java.util.Objects;

/**
 * pdf转图片/图片Base64工具类
 */
@Slf4j
public class Pdf2ImageUtil {

    /**
     * pdf文件转换成jpg图片字节数组
     *
     * @param pdfBytes 要转换的pdf文件的字节数组
     */
    private static byte[] pdf2Image(byte[] pdfBytes) throws IOException {
        PDDocument doc = null;
        ByteArrayOutputStream baos = null;
        try {
            doc = PDDocument.load(pdfBytes);
            int pageCount = doc.getNumberOfPages();
            log.info("PDF转图片流，总页数:{}", pageCount);
            PDFRenderer pdfRenderer = new PDFRenderer(doc);
            // 不知道图片的宽和高，所以先定义个null
            BufferedImage pdfImage = null;
            // pdf有多少页
            int y = 0;
            List<BufferedImage> list = new ArrayList<>(pageCount);
            // 所有页高度综合
            int totalHeight = 0;
            if (pageCount > 0) {
                for (int i = 0; i < pageCount; i++) {
                    // 每页pdf内容 注意：图片设置100dpi, 设置太高容易OOM并且转不了几页
                    BufferedImage bim = pdfRenderer.renderImageWithDPI(i, 100, ImageType.RGB);
                    totalHeight += bim.getHeight();
                    list.add(bim);
                }
            }
            for (BufferedImage bim : list) {
                // 如果是第一页需要初始化 BufferedImage
                if (Objects.isNull(pdfImage)) {
                    // 创建一个总高、总宽 的图片缓冲区
                    pdfImage = new BufferedImage(bim.getWidth(), totalHeight, BufferedImage.TYPE_INT_RGB);
                }
                // 将每页pdf画到总的pdfImage上,x坐标=0，y坐标=之前所有页的高度和，属于向下偏移
                pdfImage.getGraphics().drawImage(bim, 0, y, null);
                y += bim.getHeight();
            }
            if (pdfImage != null) {
                baos = new ByteArrayOutputStream();
                ImageIO.write(pdfImage, "jpg", baos);
                baos.flush();
                byte[] imageInByte = baos.toByteArray();
                log.info("PDF转图片流成功");
                return imageInByte;
            }
            return null;
        } catch (Exception e) {
            log.error("PDF转图片流失败：{}", e.getMessage());
            e.printStackTrace();
        } finally {
            if (ObjectUtil.isNotNull(baos)) {
                baos.close();
            }
            if (ObjectUtil.isNotNull(doc)) {
                doc.close();
            }
        }
        return null;
    }

    /**
     * pdf转图片Base64编码
     *
     * @param filePath pdf路径
     * @return 图片Base64编码
     * @throws IOException IO异常
     */
    public static String image2Base64(String filePath) throws IOException {
    	// 获取云存储图片链接的字节
        byte[] pdfBytes = HttpUtil.createGet(filePath).execute().bodyBytes();
        // 获取本地图片的字节, 方便本地测试
//        byte[] pdfBytes = Files.readAllBytes(Paths.get(filePath));
        byte[] imageBytes = Pdf2ImageUtil.pdf2Image(pdfBytes);
        return getFileContentAsBase64Urlencoded(imageBytes);
    }

    /**
     * 获取文件base64编码
     *
     * @param imageBytes 图片字节数组
     * @return base64编码信息，不带文件头
     */
    private static String getFileContentAsBase64(byte[] imageBytes) {
        return Base64.getEncoder().encodeToString(imageBytes);
    }

    /**
     * 获取文件base64 UrlEncode编码
     *
     * @param imageBytes 图片字节数组
     * @return base64编码信息，不带文件头
     * @throws IOException IO异常
     */
    private static String getFileContentAsBase64Urlencoded(byte[] imageBytes) throws IOException {
        return URLEncoder.encode(getFileContentAsBase64(imageBytes), "utf-8");
    }
}