关于pdf:pdf转图片

 <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox</artifactId>
            <version>2.0.18</version>
        </dependency>
        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>jbig2-imageio</artifactId>
            <version>3.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.pdfbox</groupId>
            <artifactId>pdfbox-tools</artifactId>
            <version>2.0.18</version>
        </dependency>

@Test
    public void pdf2image2() throws IOException {

        PDDocument pdDocument;
        FileInputStream fileInputStream = new FileInputStream("d:/test.pdf");
        pdDocument = PDDocument.load(fileInputStream);
        PDFRenderer renderer = new PDFRenderer(pdDocument);
        // 获取 PDF 页数
        int pages = pdDocument.getNumberOfPages();
        for (int i = 0; i < pages; i++) {BufferedImage image = renderer.renderImage(i, 2.5f, ImageType.BINARY, RenderDestination.PRINT);
            FileOutputStream out = new FileOutputStream("d:\\imageresult" + i + ".png");
            // PNG
            ImageIO.write(image, "png", out);

        }
        pdDocument.close();}

应用 renderImage 会小很多

aspose

  FileInputStream fileInputStream = new FileInputStream("D:\\test.pdf");
        Document pdfDocument = new Document(fileInputStream);
        Resolution resolution = new Resolution(72);
        JpegDevice jpegDevice = new JpegDevice(740, 1046, resolution, 100);
        RenderingOptions renderingOptions = new RenderingOptions();
        for (int index = 1; index <= pdfDocument.getPages().size(); index++) {
            // 输入门路
            FileOutputStream out = new FileOutputStream("d:\\image" + index + ".jpg");

            jpegDevice.process(pdfDocument.getPages().get_Item(index), out);

            out.close();}
        pdfDocument.close();

图片压缩

 File imageFile = new File("d:\\imageresult0.jpg");
        File compressedImageFile = new File("d:\\myimage_compressed.jpg");

        InputStream is = new FileInputStream(imageFile);
        OutputStream os = new FileOutputStream(compressedImageFile);

        float quality = 0.01f;

        // create a BufferedImage as the result of decoding the supplied InputStream
        BufferedImage image = ImageIO.read(is);

        // get all image writers for JPG format
        Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("jpg");

        if (!writers.hasNext())
            throw new IllegalStateException("No writers found");

        ImageWriter writer = (ImageWriter) writers.next();
        ImageOutputStream ios = ImageIO.createImageOutputStream(os);
        writer.setOutput(ios);

        ImageWriteParam param = writer.getDefaultWriteParam();

        param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
        param.setCompressionQuality(quality);
        writer.write(null, new IIOImage(image, null, null), param);

        // close all streams
        is.close();
        os.close();
        ios.close();
        writer.dispose();