java PDF2JPG

import org.apache.commons.lang3.StringUtils;
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.File;
    private static void pdfTojpg(String pdfFilePath, String jpgFilePath) {
        File pdfFile = new File(pdfFilePath);
        int idx = jpgFilePath.lastIndexOf('.');
        String jpgprefix = StringUtils.substring(jpgFilePath, 0, idx);
        int pdfdpi = 400;
        try (final PDDocument document = PDDocument.load(pdfFile, "")) {
            int size = document.getNumberOfPages();
            for (int i = 0; i < size; i++) {
                BufferedImage image = new PDFRenderer(document).renderImageWithDPI(i, pdfdpi, ImageType.RGB);
                File jpgFile = new File(jpgprefix + "_" + i + ".jpg");
                ImageIO.write(image, "jpg", jpgFile);
            }
        } catch (Exception e) {
        }
    }