这是一种实现方法，它结合了Web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
原文：http :
//www.exampledepot.com/egs/java.awt.image/Image2Buf.html
更新：如何将缓冲的图像转换为图像，反之亦然？
将生成的图形保存到PNG或JPEG文件
原文：http :
//www.exampledepot.com/egs/javax.imageio/Graphic2File.html
更新：http :
//docs.oracle.com/javase/tutorial/2d/images/saveimage.html
组合成类似这样的东西，可以将所有页面变成图像：
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 pre 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(); } } }); }}
