import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject; //导入依赖的package包/类
public void extractPatternImages(PDPatternResources pattern, String patternFormat) throws IOException
{
    COSDictionary resourcesDict = (COSDictionary) pattern.getCOSDictionary().getDictionaryObject(COSName.RESOURCES);
    if (resourcesDict == null)
        return;
    PDResources resources = new PDResources(resourcesDict);
    Map<String, PDXObject> xObjects = resources.getXObjects();
    if (xObjects == null)
        return;

    for (Map.Entry<String, PDXObject> entry : xObjects.entrySet())
    {
        PDXObject xObject = entry.getValue();
        String xObjectFormat = String.format(patternFormat, "-" + entry.getKey() + "%s", "%s");
        if (xObject instanceof PDXObjectForm)
            extractPatternImages((PDXObjectForm)xObject, xObjectFormat);
        else if (xObject instanceof PDXObjectImage)
            extractPatternImages((PDXObjectImage)xObject, xObjectFormat);
    }
}
 

import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject; //导入依赖的package包/类
public void extractAnnotationImages(PDAppearanceStream appearance, String appearanceFormat) throws IOException
{
    PDResources resources = appearance.getResources();
    if (resources == null)
        return;
    Map<String, PDXObject> xObjects = resources.getXObjects();
    if (xObjects == null)
        return;

    for (Map.Entry<String, PDXObject> entry : xObjects.entrySet())
    {
        PDXObject xObject = entry.getValue();
        String xObjectFormat = String.format(appearanceFormat, "-" + entry.getKey() + "%s", "%s");
        if (xObject instanceof PDXObjectForm)
            extractAnnotationImages((PDXObjectForm)xObject, xObjectFormat);
        else if (xObject instanceof PDXObjectImage)
            extractAnnotationImages((PDXObjectImage)xObject, xObjectFormat);
    }
}
 

import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject; //导入依赖的package包/类
/**
 *
 *
 * @param resources
 *
 * @throws IOException
 */
private void processResources(PDResources resources, TikaImageHelper helper)
throws IOException {
  if (resources == null)
    return;

  try {
    Map<String, PDXObject> xobjects = resources.getXObjects();
    if (xobjects != null) {
      Iterator<String> xobjectIter = xobjects.keySet().iterator();
      while (xobjectIter.hasNext()) {
        String key = xobjectIter.next();
        PDXObject xobject = xobjects.get(key);
        // write the images
        if (xobject instanceof PDXObjectImage) {
          PDXObjectImage image = (PDXObjectImage) xobject;
          if (ImageTools.imagePerPageRatioValid(imageCount++, pageCount)
              && ImageTools.imageSizeValid(image.getHeight(), image.getWidth())) {
            BufferedImage buffImage = image.getRGBImage();
            helper.addImage(buffImage);
          }
        }
        // maybe there are more images embedded in a form object
        else if (xobject instanceof PDXObjectForm) {
          if (ImageTools.imagePerPageRatioValid(imageCount, pageCount)) {
            PDXObjectForm xObjectForm = (PDXObjectForm) xobject;
            PDResources formResources = xObjectForm.getResources();
            processResources(formResources, helper);
          }
        }
      }
    }
  } catch (Exception e) {
    LOG.info("Shit happened", e);
  }

}
 

import org.apache.pdfbox.pdmodel.graphics.xobject.PDXObject; //导入依赖的package包/类
private void scanResources(final PDResources rList, final PDDocument doc)
      throws FileNotFoundException, IOException {
    Map<String, PDXObject> xObs = rList.getXObjects();
    for(String k : xObs.keySet()) {
       final PDXObject xObj = xObs.get(k);
       if(xObj instanceof PDXObjectForm)
            scanResources(((PDXObjectForm) xObj).getResources(), doc);
       if(!(xObj instanceof PDXObjectImage))
            continue;
       PDXObjectImage img = (PDXObjectImage) xObj;
       System.out.println("Compressing image: " + k);
       final Iterator<ImageWriter> jpgWriters = 
               ImageIO.getImageWritersByFormatName("jpeg");
       final ImageWriter jpgWriter = jpgWriters.next();
       final ImageWriteParam iwp = jpgWriter.getDefaultWriteParam();
       iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
       iwp.setCompressionQuality(compQual);
       ByteArrayOutputStream baos = new ByteArrayOutputStream();
       jpgWriter.setOutput(ImageIO.createImageOutputStream(baos));
       jpgWriter.write(null,
               new IIOImage(img.getRGBImage(), null, null), iwp);
       ByteArrayInputStream bais = 
               new ByteArrayInputStream(baos.toByteArray());
       PDJpeg jpg = new PDJpeg(doc, bais);
       xObs.put(k, jpg);
    }
    rList.setXObjects(xObs);
}