pdf 转png (多页pdf转一张png) aspose pdf jar

/**
 * 将pdf转图片
 */
public static void pdfToImage(InputStream inputStream, File imgFile) {
    try {
        long old = System.currentTimeMillis();
        System.out.println("begin..............");
        Document pdfDocument = new Document(inputStream);
        Resolution resolution = new Resolution(130);
        JpegDevice jpegDevice = new JpegDevice(resolution);
        List<BufferedImage> imageList = new ArrayList<BufferedImage>();
        List<File> fileList = new ArrayList<>();
        for (int index = 1; index <= pdfDocument.getPages().size(); index++) {
            File file = File.createTempFile("tempFile", "png");
            FileOutputStream fileOS = new FileOutputStream(file);
            jpegDevice.process(pdfDocument.getPages().get_Item(index), fileOS);
            fileOS.close();
            imageList.add(ImageIO.read(file));
            fileList.add(file);
        }
        //临时文件删除
        BufferedImage mergeImage = mergeImage(false, imageList);
        ImageIO.write(mergeImage, "png", imgFile);
        long now = System.currentTimeMillis();
        System.out.println("共耗时：" + ((now - old) / 1000.0) + "秒");
        //删除临时文件
        for (File f : fileList) {
            f.delete();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

}

/**
 * 合并任数量的图片成一张图片
 *
 * @param isHorizontal true代表水平合并，fasle代表垂直合并
 * @param imgs         待合并的图片数组
 * @return
 * @throws IOException
 */
public static BufferedImage mergeImage(boolean isHorizontal, List<BufferedImage> imgs) throws IOException {
    // 生成新图片
    BufferedImage destImage = null;
    // 计算新图片的长和高
    int allw = 0, allh = 0, allwMax = 0, allhMax = 0;
    // 获取总长、总宽、最长、最宽
    for (int i = 0; i < imgs.size(); i++) {
        BufferedImage img = imgs.get(i);
        allw += img.getWidth();

        if (imgs.size() != i + 1) {
            allh += img.getHeight() + 5;
        } else {
            allh += img.getHeight();
        }


        if (img.getWidth() > allwMax) {
            allwMax = img.getWidth();
        }
        if (img.getHeight() > allhMax) {
            allhMax = img.getHeight();
        }
    }
    // 创建新图片
    if (isHorizontal) {
        destImage = new BufferedImage(allw, allhMax, BufferedImage.TYPE_INT_RGB);
    } else {
        destImage = new BufferedImage(allwMax, allh, BufferedImage.TYPE_INT_RGB);
    }
    Graphics2D g2 = (Graphics2D) destImage.getGraphics();
    g2.setBackground(Color.LIGHT_GRAY);
    g2.clearRect(0, 0, allw, allh);
    g2.setPaint(Color.RED);

    // 合并所有子图片到新图片
    int wx = 0, wy = 0;
    for (int i = 0; i < imgs.size(); i++) {
        BufferedImage img = imgs.get(i);
        int w1 = img.getWidth();
        int h1 = img.getHeight();
        // 从图片中读取RGB
        int[] ImageArrayOne = new int[w1 * h1];
        // 逐行扫描图像中各个像素的RGB到数组中
        ImageArrayOne = img.getRGB(0, 0, w1, h1, ImageArrayOne, 0, w1);
        if (isHorizontal) {
            // 水平方向合并
            // 设置上半部分或左半部分的RGB
            destImage.setRGB(wx, 0, w1, h1, ImageArrayOne, 0, w1);
        } else {
            // 垂直方向合并
            // 设置上半部分或左半部分的RGB
            destImage.setRGB(0, wy, w1, h1, ImageArrayOne, 0, w1);
        }
        wx += w1;
        wy += h1 + 5;
    }


    return destImage;
}