关于pdf:Pdf-转换-图片

PDDocument document = null;        String pdfdir = "d:/pdf2image/";        File file = new File(pdfdir);        if(!file.exists()||!file.isDirectory()){            System.out.println("the diretory is not exist");            return;        }        File [] files = file.listFiles();        for(File pdf :files){            String filepath = pdf.getAbsolutePath();            if(!filepath.contains(".pdf")){                continue;            }            String filename = pdf.getName();            String imageNamePrefix = filename.substring(0,filename.lastIndexOf("."));            File imagedir = new File(pdfdir+imageNamePrefix);            if(!imagedir.exists()){                imagedir.mkdir();            }            InputStream inputStream = new FileInputStream(pdf);            document = PDDocument.load(inputStream);            PDFRenderer renderer = new PDFRenderer(document);            int pageCount = document.getNumberOfPages();            System.out.println("共 "+pageCount+" 页.");            for (int i = 0; i < pageCount; i++) {                BufferedImage image = renderer.renderImage(i, 1.9f);                ImageIO.write(image, "jpg", new File(pdfdir+imageNamePrefix+File.separator+ i + ".jpg"));            }        }

<dependency>            <groupId>org.apache.pdfbox</groupId>            <artifactId>pdfbox</artifactId>            <version>2.0.18</version>        </dependency>