Question

我正在使用iText库来合并单个pdf。但个人pdf总是出现在页面底部。任何指针如何使它显示在中间或顶部。我已经从http://viralpatel.net/blogs/itext-tutorial-merge-split-pdf-files-using-itext-jar/调整了我的代码 enter image description here

public static void concatPDFs(OutputStream outputStream, boolean paginate) {

        Document document = new Document();
        try {
            List<InputStream> pdfs = listPdf;
            List<PdfReader> readers = new ArrayList<PdfReader>();
            int totalPages = 0;
            Iterator<InputStream> iteratorPDFs = pdfs.iterator();

            // Create Readers for the pdfs.
            while (iteratorPDFs.hasNext()) {
                InputStream pdf = iteratorPDFs.next();
                PdfReader pdfReader = new PdfReader(pdf);
                readers.add(pdfReader);
                totalPages += pdfReader.getNumberOfPages();
            }
            // Create a writer for the outputstream
            PdfWriter writer = PdfWriter.getInstance(document, outputStream);

            document.open();
            BaseFont bf = BaseFont.createFont(BaseFont.HELVETICA,
                    BaseFont.CP1252, BaseFont.NOT_EMBEDDED);
            PdfContentByte cb = writer.getDirectContent(); // Holds the PDF
            // data

            PdfImportedPage page;
            int currentPageNumber = 0;
            int pageOfCurrentReaderPDF = 0;
            Iterator<PdfReader> iteratorPDFReader = readers.iterator();

            // Loop through the PDF files and add to the output.
            while (iteratorPDFReader.hasNext()) {
                PdfReader pdfReader = iteratorPDFReader.next();

                // Create a new page in the target for each source page.
                while (pageOfCurrentReaderPDF < pdfReader.getNumberOfPages()) {
                    document.newPage();
                    pageOfCurrentReaderPDF++;
                    currentPageNumber++;
                    page = writer.getImportedPage(pdfReader,
                            pageOfCurrentReaderPDF);
                    cb.addTemplate(page, 0, 0);

                    // Code for pagination.
                    if (paginate) {
                        cb.beginText();
                        cb.setFontAndSize(bf, 9);
                        cb.showTextAligned(PdfContentByte.ALIGN_CENTER, ""
                                + currentPageNumber + " of " + totalPages, 520,
                                5, 0);
                        cb.endText();
                    }
                }
                pageOfCurrentReaderPDF = 0;
            }
            outputStream.flush();
            document.close();
            outputStream.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (document.isOpen())
                document.close();
            try {
                if (outputStream != null)
                    outputStream.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
    }

Answer 1

首先要了解坐标系。 PDF坐标系（0,0）表示PDF页面的左下角。

您可以计算插入页面模板的新“y”位置，如下所示：

y =新文件高度 - 导入的页面高度

然后您可以将代码更改为：

cb.addTemplate(page, 0, y);

Answer 2

合并PDF文件的最佳方法是遵循iText开发人员的说明..

https://stackoverflow.com/a/24359217/2865036

就像他说的那样，PDF文件的格式不会改变

Java：iText库PDF合并，pdf始终位于页面底部

2 个答案: