使用pdfbox实现pdf转image

序

使用soffice的命令把pdf转image的话，默认只能转一页的，这个有点费劲，因而也不打算沿用soffice的方案了，改用pdfbox来实现。

maven

<dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.4</version>
        </dependency>

        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox-tools</artifactId>
            <version>2.0.4</version>
        </dependency>

转换

public static List<BufferedImage> convertToImage(File file) throws IOException {
        PDDocument document = PDDocument.load(file);
        PDFRenderer pdfRenderer = new PDFRenderer(document);
        List<BufferedImage> bufferedImageList = new ArrayList<>();

        for (int page = 0;page<document.getNumberOfPages();page++){
            BufferedImage img = pdfRenderer.renderImageWithDPI(page, 300, ImageType.RGB);
            bufferedImageList.add(img);
        }
        document.close();

        return bufferedImageList;
    }

concat

public static BufferedImage concat(BufferedImage[] images) throws IOException {
        int heightTotal = 0;
        for(int j = 0; j < images.length; j++) {
            heightTotal += images[j].getHeight();
        }

        int heightCurr = 0;
        BufferedImage concatImage = new BufferedImage(images[0].getWidth(), heightTotal, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = concatImage.createGraphics();
        for(int j = 0; j < images.length; j++) {
            g2d.drawImage(images[j], 0, heightCurr, null);
            heightCurr += images[j].getHeight();
        }
        g2d.dispose();

        return concatImage;
}

小结

这样基本就大功告成了，不足的地方是性能过低，有待优化。