itext 7 如何合并PDF？

Question

I have a Problem and need your help. I'm running itext 7.0.2. java and i'm trying to merge a list ArrayList of type PdfDocument to one single pdf.

I tried the following:

        ByteArrayOutputStream bosGes = new ByteArrayOutputStream();
        PdfWriter writerGes = new PdfWriter(bosGes);
        PdfDocument docGes = new PdfDocument(writerGes);
        ArrayList<PdfDocument> pdfs = AListOfSomePreviousCreatedPdfDocuments;

        for (int i=0; i < pdfs.size(); i++) {
            PdfDocument d = pdfs.get(i);
            PdfPage p = d.getFirstPage().copyTo(docGes);
            docGes.addPage(p);
            d.close();
        }

Resulting in this error:

com.itextpdf.kernel.PdfException: Cannot copy indirect object from the document that is being written.

Then I tried the following:

        ByteArrayOutputStream bosGes = new ByteArrayOutputStream();
        PdfWriter writerGes = new PdfWriter(bosGes);
        PdfDocument docGes = new PdfDocument(writerGes);

        for (int i=0; i < pdfs.size(); i++) {
            PdfDocument d = pdfs.get(i);
            docGes.addPage(d.getFirstPage());
            d.close();
        }

com.itextpdf.kernel.PdfException: Page com.itextpdf.kernel.pdf.PdfPage@1d85315f cannot be added to document com.itextpdf.kernel.pdf.PdfDocument@32ae81bb, because it belongs to document com.itextpdf.kernel.pdf.PdfDocument@4b8d06af.

What I have to do, to merge this PdfDocuments (each one has only one page) to one single Pdf?

---

OK, I'm going nuts. Explaining it from the beginning.

I create pdf-forms like this

        ArrayList<PdfDocument> pdfs = new ArrayList<PdfDocument>();
        while (rs.next()) {
            URL fullPath = context.getResource("/formulare/kontrollbogen.pdf");
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            PdfWriter writer = new PdfWriter(bos);
            PdfReader reader = new PdfReader(fullPath.getFile());
            PdfDocument doc = new PdfDocument(reader, writer);
            PdfAcroForm form = PdfAcroForm.getAcroForm(doc, true);

            String firma = rs.getString("firma");
            if (firma != null && !firma.equals("")) {
                form.getField("firma").setValue(firma);
            }
                .
                .
                .
            pdfs.add(doc);
       }

Then I want to merge this PdfDocuments in my ArrayList like this:

        ByteArrayOutputStream bosGes = new ByteArrayOutputStream();
        PdfWriter writerGes = new PdfWriter(bosGes);
        PdfDocument resultDoc = new PdfDocument(writerGes);

        for (int i=0; i < pdfs.size(); i++) {
            PdfReader r = pdfs.get(i).getReader();
            PdfDocument sourceDoc1 = new PdfDocument(r);
            int n1 = sourceDoc1.getNumberOfPages();             

            for (int j = 1; j <= n1; j++) {
                PdfPage page = sourceDoc1.getPage(j).copyTo(resultDoc);
                resultDoc.addPage(page);
            }
            sourceDoc1.close();
        }

        resultDoc.close();

Doesn't work. Result is a pdf with more pages but forms are not filled out.

So I tried RTFM and tried Bruno's example with merging flattened forms but result is always a pdf with empty forms.

Can anyone help to convert the pdf-forms (all the same form) in my ArrayList to one single pdf?

---

I tried Bruno's tip but it doesn't work. What I did is:

        //Initialize PDF document with output intent
        PdfDocument pdf = new PdfDocument(writerGes);
        PdfMerger merger = new PdfMerger(pdf);
        //Add pages from the first document
        PdfDocument firstSourcePdf = pdfs.get(0);
        merger.merge(firstSourcePdf, 1, firstSourcePdf.getNumberOfPages());
        //Add pages from the second pdf document
        PdfDocument secondSourcePdf = pdfs.get(1);
        merger.merge(secondSourcePdf, 1, secondSourcePdf.getNumberOfPages());
        firstSourcePdf.close();
        secondSourcePdf.close();
        pdf.close();

but it ends up with this error again:

com.itextpdf.kernel.PdfException: Cannot copy indirect object from the document that is being written.

Is this perhaps because my pdf's are forms and I have to reset the values when merging?

Answer 1

this is how I merged 2 pdf documents together

if (1 <= listOfFiles.Count)
                    {

                        masterSrc = subPath + "/" + date + " - " + dateEnd + ".pdf";

                        PdfDocument merged = new PdfDocument(new PdfWriter(Server.MapPath(masterSrc)));
                        
                        for (int a = 0; a < listOfFiles.Count; a++)
                        {
                            PdfDocument origPdf2 = new PdfDocument(new PdfReader(Server.MapPath(listOfFiles[a])));
                            PdfMerger merger = new PdfMerger(merged);
                            merger.Merge(origPdf2, 1, origPdf2.GetNumberOfPages());

                        }
                        merged.Close();
                    }