java - 使用 iText5 从 PDF 中提取文本和图像

Question

我需要帮助使用 Java 库 iText5 从 PDF 文件中提取文本和图像，并映射或引用提取文本中的图像。如果 iText5 是错误的工具，请推荐另一个具有相同功能的 Java 库来告诉我。

这就是我目前所做的

import java.io.IOException;
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.parser.PdfReaderContentParser;
import com.itextpdf.text.pdf.parser.PdfTextExtractor;
import com.itextpdf.text.Paragraph;

public class Iconverter {

    /**
     * @param args
     */
    static int PAGE_NUMBER;


    /** The new document to which we've added a border rectangle. */
    public static final String RESULT = "/home/sarah/Java for Dummies 4th Edition/Img%s.%s";
    public static void main(String[] args) {
        String docText = "";
        String pdfName = "/home/sarah/Java for Dummies 4th Edition.pdf";
        Document document = new Document();
        document.open();
        try {
            PdfReader reader = new PdfReader(pdfName);
            PAGE_NUMBER = reader.getNumberOfPages();
            for(int i = 1; i <=PAGE_NUMBER; i++){
                docText = PdfTextExtractor.getTextFromPage(reader, i);  
            }
            extractImages(pdfName);     
            document.add(new Paragraph(".."));
        } catch (Exception e) {
            e.printStackTrace();
        }
        document.close();
    }
    /**
     * Parses a PDF and extracts all the images.
     * @param src the source PDF
     * @param dest the resulting PDF
     */
    public static void extractImages(String filename) throws IOException, DocumentException {
        PdfReader reader = new PdfReader(filename);
        PdfReaderContentParser parser = new PdfReaderContentParser(reader);
        MyImageRenderListener listener = new MyImageRenderListener(RESULT);
        for (int i = 1; i <= PAGE_NUMBER; i++) {
            parser.processContent(i, listener);
        }
    }   
}

import java.awt.image.BufferedImage;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import com.itextpdf.text.pdf.PdfName;
import com.itextpdf.text.pdf.parser.ImageRenderInfo;
import com.itextpdf.text.pdf.parser.PdfImageObject;
import com.itextpdf.text.pdf.parser.RenderListener;
import com.itextpdf.text.pdf.parser.TextRenderInfo;

public class MyImageRenderListener implements RenderListener {

    /** The new document to which we've added a border rectangle. */
    protected String path = "";

    /**
     * Creates a RenderListener that will look for images.
     */
    public MyImageRenderListener(String path) {
        this.path = path;
    }

    /**
     * @see com.itextpdf.text.pdf.parser.RenderListener#beginTextBlock()
     */
    public void beginTextBlock() {
    }

    /**
     * @see com.itextpdf.text.pdf.parser.RenderListener#endTextBlock()
     */
    public void endTextBlock() {
    }

    /**
     * @see com.itextpdf.text.pdf.parser.RenderListener#renderImage(
     *     com.itextpdf.text.pdf.parser.ImageRenderInfo)
     */
    public void renderImage(ImageRenderInfo renderInfo) {
        try {
            String filename;
            FileOutputStream os;
            PdfImageObject image = renderInfo.getImage();
            PdfName filter = (PdfName)image.get(PdfName.FILTER);
            if (PdfName.DCTDECODE.equals(filter)) {
                filename = String.format(path, renderInfo.getRef().getNumber(), "JPG");
                os = new FileOutputStream(filename);
                os.write(image.getStreamBytes());
                os.flush();
                os.close();
            }
            else if (PdfName.JPXDECODE.equals(filter)) {
                filename = String.format(path, renderInfo.getRef().getNumber(), "jp2");
                os = new FileOutputStream(filename);
                os.write(image.getStreamBytes());
                os.flush();
                os.close();
            }
            else if (PdfName.JBIG2DECODE.equals(filter)) {
                // ignore: filter not supported.
            }
            else {
                BufferedImage awtimage = renderInfo.getImage().getBufferedImage();
                if (awtimage != null) {
                    filename = String.format(path, renderInfo.getRef().getNumber(), "png");
                    ImageIO.write(awtimage, "png", new FileOutputStream(filename));
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * @see com.itextpdf.text.pdf.parser.RenderListener#renderText(
     *     com.itextpdf.text.pdf.parser.TextRenderInfo)
     */
    public void renderText(TextRenderInfo renderInfo) {
    }
}

Answer 1

作为 iText 的替代品，Apache PDFBox可以帮助你。

看看这些类:

org.apache.pdfbox.ExtractImages

org.apache.pdfbox.ExtractText