• 主要代码逻辑

//判断生成路径
File fileDir = new File("./generatePng");
if (!fileDir.exists()) {
    fileDir.mkdirs();
}

String workPermitId = 唯一标识;

Document doc = new Document(word文档路径);

if (doc.getPageCount() > 1) {
    //多张
    for (int i = 0; i < doc.getPageCount(); i++) {
        BufferedImage image = doc.saveToImages(i, ImageType.Bitmap);
        File file = new File("./generatePng/" + workPermitId + (i + 1) + ".png");
        ImageIO.write(image, "PNG", file);
    }
    //拼接图片
    boolean isOk = mergeImage(workPermitId, doc.getPageCount(), 2, System.getProperty("user.dir") + "/generatePng/" + workPermitId + ".png");
    if (!isOk) {
        return AjaxResult.error("作业票图片生成失败，请重新尝试或确认是否存在word文档");
    }
} else {
    //单张
    BufferedImage image = doc.saveToImages(0, ImageType.Bitmap);
    File file = new File("./generatePng/" + workPermitId + ".png");
    ImageIO.write(image, "PNG", file);
}

• 拼接图片方法

/**
 * 拼接图片（注：图片需长宽一致）
 *
 * @param len        图片数量
 * @param type       1：横向拼接 2：纵向拼接
 * @param targetFile 合成新的图片地址
 */
public static boolean mergeImage(String workPermitId,Integer len, int type, String targetFile) {

    // File[] src = new File[len];
    BufferedImage[] images = new BufferedImage[len];
    int[][] ImageArrays = new int[len][];

    for (int i = 0; i < len; i++) {
        try {
            // src[i] = new File(files[i]);
            images[i] = ImageIO.read(new File(System.getProperty("user.dir") + "/generatePng/" + workPermitId + (i + 1) + ".png"));
        } catch (Exception e) {
            log.error(e.getMessage(), e);
        }

        int width = images[i].getWidth();
        int height = images[i].getHeight();
        ImageArrays[i] = new int[width * height];
        ImageArrays[i] = images[i].getRGB(0, 0, width, height, ImageArrays[i], 0, width);
    }

    int newHeight = 0;
    int newWidth = 0;
    for (int i = 0; i < images.length; i++) {
        // 横向
        if (type == 1) {
            newHeight = newHeight > images[i].getHeight() ? newWidth : images[i].getHeight();
            // 错误代码，原先没有添加+ 号
            newWidth += images[i].getWidth();
        } else if (type == 2) {
            // 纵向
            newWidth = newHeight > images[i].getWidth() ? newWidth : images[i].getWidth();
            newHeight += images[i].getHeight();
        }
    }

    if (type == 1 && newWidth < 1) {
        return false;
    }

    if (type == 2 && newHeight < 1) {
        return false;
    }


    try {
        BufferedImage ImageNew = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
        int height_i = 0;
        int width_i = 0;
        for (int i = 0; i < images.length; i++) {
            if (type == 1) {
                ImageNew.setRGB(width_i, 0, images[i].getWidth(), newHeight, ImageArrays[i], 0, images[i].getWidth());
                width_i += images[i].getWidth();
            } else if (type == 2) {
                ImageNew.setRGB(0, height_i, newWidth, images[i].getHeight(), ImageArrays[i], 0, newWidth);
                height_i += images[i].getHeight();
            }
        }
        // 输出想要的图片
        ImageIO.write(ImageNew, targetFile.split("\\.")[1], new File(targetFile));
        return true;
    } catch (Exception e) {
        log.error(e.getMessage(), e);
        return false;
    }
}