使用PDFBox拆分大型Pdf文件会获得大量结果文件

问题描述

我正在使用pdfbox处理一些大型pdf文件（最多100MB和大约2000页）。有些页面包含QR码，我想将这些文件分成较小的页面，页面从一个QR码到下一个。
我得到了这个，但结果文件大小与源文件相同。我的意思是，如果我将一个100MB的pdf文件剪切成十个文件，我将得到10个文件，每个100MB。

I am processing some large pdf files, (up to 100MB and about 2000 pages), with pdfbox. Some of the pages contain a QR code, I want to split those files into smaller ones with the pages from one QR code to the next.I got this, but the result file sizes are the same as the source file. I mean, if I cut a 100MB pdf file into a ten files I am getting ten files 100MB each.

这是代码：

 PDDocument documentoPdf =
        PDDocument.loadNonSeq(new File("myFile.pdf"),
                           new RandomAccessFile(new File("./tmp/temp"), "rw"));

    int numPages = documentoPdf.getNumberOfPages();
    List pages = documentoPdf.getDocumentCatalog().getAllPages();

    int previusQR = 0;
    for(int i =0; i<numPages; i++){
       PDPage page = (PDPage) pages.get(i);
       BufferedImage firstPageImage =
           page.convertToImage(BufferedImage.TYPE_USHORT_565_RGB , 200);

       String qrText = readQRWithQRCodeMultiReader(firstPageImage, hintMap);

       if(qrText != null and i!=0){
         PDDocument outputDocument = new PDDocument();
         for(int j = previusQR; j<i; j++){
           outputDocument.importPage((PDPage)pages.get(j));
          }
         File f = new File("./splitting_files/"+previusQR+".pdf");
         outputDocument.save(f);
         outputDocument.close();
         documentoPdf.close();
    }

我还尝试使用以下代码存储新文件：

I also tried the following code for storing the new file:

PDDocument outputDocument = new PDDocument();

for(int j = previusQR; j<i; j++){
 PDStream src = ((PDPage)pages.get(j)).getContents();
 PDStream streamD = new PDStream(outputDocument);
 streamD.addCompression();

 PDPage newPage = new PDPage(new
           COSDictionary(((PDPage)pages.get(j)).getCOSDictionary()));
 newPage.setContents(streamD);

 byte[] buf = new byte[10240];
 int amountRead = 0;
 InputStream is = null;
 OutputStream os = null;
 is = src.createInputStream();
 os = streamD.createOutputStream();
 while((amountRead = is.read(buf,0,10240)) > -1) {
    os.write(buf, 0, amountRead);
  }

 outputDocument.addPage(newPage);
}

File f = new File("./splitting_files/"+previusQR+".pdf");

outputDocument.save(f);
outputDocument.close();

但是这段代码会创建缺少某些内容并且大小与原始文件大小相同的文件。

But this code creates files which lacks some content and also have the same size than the original.

如何从较大的pdf文件创建较小的pdf文件？
是否可以使用PDFBox？有没有其他库我可以将单个页面转换为图像（用于qr识别），还允许我将一个大的pdf文件拆分成较小的文件？

How can I create smaller pdfs files from a larger one?Is it posible with PDFBox? Is there any other library with which I can transform a single page into an image (for qr recognition), and also allows me to split a big pdf file into smaller ones?

Thx！

推荐答案

Thx！ Tilman你是对的，PDFSplit命令生成较小的文件。我检查了PDFSplit代码，发现它删除了页面链接以避免不需要的资源。

Thx! Tilman you are right, the PDFSplit command generates smaller files. I checked the PDFSplit code out and found that it removes the page links to avoid not needed resources.

从Splitter.class中提取的代码：

Code extracted from Splitter.class :

private void processAnnotations(PDPage imported) throws IOException
    {
        List<PDAnnotation> annotations = imported.getAnnotations();
        for (PDAnnotation annotation : annotations)
        {
            if (annotation instanceof PDAnnotationLink)
            {
                PDAnnotationLink link = (PDAnnotationLink)annotation;
                PDDestination destination = link.getDestination();
                if (destination == null && link.getAction() != null)
                {
                    PDAction action = link.getAction();
                    if (action instanceof PDActionGoTo)
                    {
                        destination = ((PDActionGoTo)action).getDestination();
                    }
                }
                if (destination instanceof PDPageDestination)
                {
                    // TODO preserve links to pages within the splitted result
                    ((PDPageDestination) destination).setPage(null);
                }
            }
            else
            {
                // TODO preserve links to pages within the splitted result
                annotation.setPage(null);
            }
        }
    }

所以最终我的代码看起来像这个：

So eventually my code looks like this:

PDDocument documentoPdf =
        PDDocument.loadNonSeq(new File("docs_compuestos/50.pdf"), new RandomAccessFile(new File("./tmp/t"), "rw"));

        int numPages = documentoPdf.getNumberOfPages();
        List pages = documentoPdf.getDocumentCatalog().getAllPages();


        int previusQR = 0;
        for(int i =0; i<numPages; i++){
            PDPage firstPage = (PDPage) pages.get(i);
            String qrText ="";


            BufferedImage firstPageImage = firstPage.convertToImage(BufferedImage.TYPE_USHORT_565_RGB , 200);


            firstPage =null;

            try {
                qrText = readQRWithQRCodeMultiReader(firstPageImage, hintMap);
            } catch (NotFoundException e) {
                e.printStackTrace();
            } finally {
                firstPageImage = null;
            }


        if(i != 0 && qrText!=null){
                    PDDocument outputDocument = new PDDocument();
                    outputDocument.setDocumentInformation(documentoPdf.getDocumentInformation());
                    outputDocument.getDocumentCatalog().setViewerPreferences(
                            documentoPdf.getDocumentCatalog().getViewerPreferences());


                    for(int j = previusQR; j<i; j++){
                        PDPage importedPage = outputDocument.importPage((PDPage)pages.get(j));

                        importedPage.setCropBox( ((PDPage)pages.get(j)).findCropBox() );
                        importedPage.setMediaBox( ((PDPage)pages.get(j)).findMediaBox() );
                        // only the resources of the page will be copied
                        importedPage.setResources( ((PDPage)pages.get(j)).getResources() );
                        importedPage.setRotation( ((PDPage)pages.get(j)).findRotation() );

                        processAnnotations(importedPage);


                    }


                    File f = new File("./splitting_files/"+previusQR+".pdf");

                    previusQR = i;

                    outputDocument.save(f);
                    outputDocument.close();
                }
            }


        }

非常感谢!!

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