Java：PDF图片抽取的两种方法

在Java中，可以使用Apache PDFBox和Java ImageIO库来抽取PDF中的图片。以下是两种方法的示例代码：

方法一：使用Apache PDFBox

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.graphics.image.PDImageXObject;
 
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.List;
 
public class ExtractImages {
    public static void main(String[] args) throws IOException {
        File file = new File("example.pdf");
        PDDocument document = PDDocument.load(file);
        List<PDPage> pages = document.getDocumentCatalog().getAllPages();
 
        for (PDPage page : pages) {
            PDResources resources = page.getResources();
            for (PDImageXObject image : resources.getImages()) {
                BufferedImage bufferedImage = image.toImage();
                String extension = "png"; // or "jpg" if image is not a PNG
                File outputFile = new File("extracted_image." + extension);
                ImageIO.write(bufferedImage, extension, outputFile);
            }
        }
        document.close();
    }
}

方法二：使用Java Advanced Imaging (JAI)

import javax.media.jai.JAI;
import javax.media.jai.RenderedOp;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;
 
public class ExtractImages {
    public static void main(String[] args) throws IOException {
        File file = new File("example.pdf");
        Iterator<ImageReader> readers = ImageIO.getImageReadersByFormatName("PDF");
        ImageReader reader = readers.next();
        ImageInputStream iis = ImageIO.createImageInputStream(file);
        reader.setInput(iis);
 
        for (int i = 0; i < reader.getNumImages(true); i++) {
            BufferedImage image = reader.read(i);
            String extension = "png"; // or "jpg" if image is not a PNG
            File outputFile = new File("extracted_image." + extension);
            Ima