Question

我需要将任意PDF文档的页面导出为jpeg / png / etc格式的一系列单独图像。我需要在Java中执行此操作。

虽然我确实知道iText，PDFBox和其他各种java pdf库，但我希望有一个指向某个工作示例的指针，或者一些操作方法。

感谢。

Answer 1

这是一种方法，它结合了网络上的一些代码片段。

如何将PDF绘制到图像中？

https://pdf-renderer.dev.java.net/examples.html

从图像创建缓冲图像

ORIGINAL：http://www.exampledepot.com/egs/java.awt.image/Image2Buf.html

更新：How to convert buffered image to image and vice-versa?

将生成的图形保存为PNG或JPEG文件

ORIGINAL：http://www.exampledepot.com/egs/javax.imageio/Graphic2File.html

更新：http://docs.oracle.com/javase/tutorial/2d/images/saveimage.html

将这样的内容组合成一个可以将所有页面转换为图像的内容：

import com.sun.pdfview.PDFFile;
import com.sun.pdfview.PDFPage;

import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Transparency;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import javax.swing.*;
import javax.imageio.*;
import java.awt.image.*;

public class ImageMain {
    public static void setup() throws IOException {
        // load a pdf from a byte buffer
        File file = new File("test.pdf");
        RandomAccessFile raf = new RandomAccessFile(file, "r");
        FileChannel channel = raf.getChannel();
        ByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
        PDFFile pdffile = new PDFFile(buf);
        int numPgs = pdffile.getNumPages();
        for (int i = 0; i < numPgs; i++) {
            // draw the first page to an image
            PDFPage page = pdffile.getPage(i);
            // get the width and height for the doc at the default zoom
            Rectangle rect = new Rectangle(0, 0, (int) page.getBBox().getWidth(), (int) page.getBBox().getHeight());
            // generate the image
            Image img = page.getImage(rect.width, rect.height, // width & height
                    rect, // clip rect
                    null, // null for the ImageObserver
                    true, // fill background with white
                    true // block until drawing is done
                    );
            // save it as a file
            BufferedImage bImg = toBufferedImage(img);
            File yourImageFile = new File("page_" + i + ".png");
            ImageIO.write(bImg, "png", yourImageFile);
        }
    }

    // This method returns a buffered image with the contents of an image
    public static BufferedImage toBufferedImage(Image image) {
        if (image instanceof BufferedImage) {
            return (BufferedImage) image;
        }
        // This code ensures that all the pixels in the image are loaded
        image = new ImageIcon(image).getImage();
        // Determine if the image has transparent pixels; for this method's
        // implementation, see e661 Determining If an Image Has Transparent
        // Pixels
        boolean hasAlpha = hasAlpha(image);
        // Create a buffered image with a format that's compatible with the
        // screen
        BufferedImage bimage = null;
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        try {
            // Determine the type of transparency of the new buffered image
            int transparency = Transparency.OPAQUE;
            if (hasAlpha) {
                transparency = Transparency.BITMASK;
            }
            // Create the buffered image
            GraphicsDevice gs = ge.getDefaultScreenDevice();
            GraphicsConfiguration gc = gs.getDefaultConfiguration();
            bimage = gc.createCompatibleImage(image.getWidth(null), image.getHeight(null), transparency);
        } catch (HeadlessException e) {
            // The system does not have a screen
        }
        if (bimage == null) {
            // Create a buffered image using the default color model
            int type = BufferedImage.TYPE_INT_RGB;
            if (hasAlpha) {
                type = BufferedImage.TYPE_INT_ARGB;
            }
            bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), type);
        }
        // Copy image to buffered image
        Graphics g = bimage.createGraphics();
        // Paint the image onto the buffered image
        g.drawImage(image, 0, 0, null);
        g.dispose();
        return bimage;
    }

    public static boolean hasAlpha(Image image) {
        // If buffered image, the color model is readily available
        if (image instanceof BufferedImage) {
            BufferedImage bimage = (BufferedImage) image;
            return bimage.getColorModel().hasAlpha();
        }
        // Use a pixel grabber to retrieve the image's color model;
        // grabbing a single pixel is usually sufficient
        PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
        try {
            pg.grabPixels();
        } catch (InterruptedException e) {
        }
        // Get the image's color model
        ColorModel cm = pg.getColorModel();
        return cm.hasAlpha();
    }

    public static void main(final String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                try {
                    ImageMain.setup();
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        });
    }
}

Answer 2

如果你考虑JPedal PDF库，它内置并记录了https://support.idrsolutions.com/hc/en-us/articles/115001978091-Convert-PDF-Files-to-Image

的示例源代码

Answer 3

如果您发现太阳渲染器不适用于所有PDF文档，您可以考虑使用jPDFImages。

为了提高效率，您应该将每个PDF页面转换为缓冲图像，然后从中转换为您需要的各种图像格式。这将避免必须从PDF转换为每种格式的图像。

以下是使用jPDFImages从PDF转换为缓冲图像的链接： http://kbdeveloper.qoppa.com/jpdfimages/codesampleconvertpdfpageintobufferedimageinjava

对于每个页面图像，您只需导出为不同的图像格式： ImageIO.write（pageBufferedImage，“JPEG”，outputFile）; ImageIO.write（pageBufferedImage，“PNG”，outputFile）; 等...

Answer 4

有不同的库可以做到这一点。我用PDFBox实现了这个目标。但在我看来，最有效的解决方案是使用ghostscript。但如果您认为需要一个简单的解决方案，请使用ImageMagick。但ImageMagick在内部调用ghostscript。使用ghostscript或imagemagick可以为您提供更好的解决方案。它比任何其他库快得多。

Answer 5

PDF到位图（Android兼容代码）

File pdfFile = new File(filePath);
PdfRenderer renderer = new PdfRenderer(ParcelFileDescriptor.open(pdfFile, ParcelFileDescriptor.MODE_READ_ONLY));

final int pageCount = renderer.getPageCount();
//Currently for a page, iterate for all the pages
PdfRenderer.Page page = renderer.openPage(pageCount);
int width =  page.getWidth();
int height = page.getHeight();

Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

Bitmap to PNG (or any other format)

Answer 6

从1而不是0开始你的for循环。你的问题将会解决。

将PDF页面导出为Java中的一系列图像

6 个答案: