<!--   pdf讀取     -->
        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.1</version>
        </dependency>

        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>fontbox</artifactId>
            <version>2.0.1</version>
        </dependency>

	public String getSinglePicBase64Contracts(String fileUrl) throws IOException {
        byte[] pdfBytes = HttpUtil.createGet(fileUrl).execute().bodyBytes();
        InputStream inputStream = new ByteArrayInputStream(pdfBytes);
        PDDocument doc = PDDocument.load(inputStream);
        PDFRenderer pdfRenderer = new PDFRenderer(doc);
        List<BufferedImage> imageList = new ArrayList<>(doc.getNumberOfPages());
        int maxWidth = 0;
        int totalHeight = 0;
        for (int i = 0; i < doc.getNumberOfPages(); i++) {
            BufferedImage image = pdfRenderer.renderImage(i, 1.25f);
            imageList.add(image);
            if (image.getWidth() > maxWidth) {
                maxWidth = image.getWidth();
            }
            totalHeight += image.getHeight();
        }
        // 繪制結(jié)果
        BufferedImage result = new BufferedImage(maxWidth, totalHeight, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = result.createGraphics();
        int nowHeight = 0;
        for (BufferedImage bufferedImage : imageList) {
        	// padding 為頁面的左邊距
            int padding = (maxWidth - bufferedImage.getWidth()) / 2;
            g2d.drawImage(bufferedImage, padding, nowHeight, null);
            nowHeight += bufferedImage.getHeight();
        }
        ByteArrayOutputStream outputStream =  new ByteArrayOutputStream();
        ImageIO.write(result, "png", outputStream);
        String singlePicBase64 = "data:image/png;base64," + Base64.encodeBase64String(outputStream.toByteArray());
        return singlePicBase64;
    }