可以使用iText连接/合并pdf的函数 - 导致一些问题 [英] function that can use iText to concatenate / merge pdfs together - causing some issues

问题描述

我正在使用以下代码使用iText将PDF合并在一起：

I'm using the following code to merge PDFs together using iText:

public static void concatenatePdfs(List<File> listOfPdfFiles, File outputFile) throws DocumentException, IOException {
        Document document = new Document();
        FileOutputStream outputStream = new FileOutputStream(outputFile);
        PdfWriter writer = PdfWriter.getInstance(document, outputStream);
        document.open();
        PdfContentByte cb = writer.getDirectContent();
        for (File inFile : listOfPdfFiles) {
            PdfReader reader = new PdfReader(inFile.getAbsolutePath());
            for (int i = 1; i <= reader.getNumberOfPages(); i++) {
                document.newPage();
                PdfImportedPage page = writer.getImportedPage(reader, i);
                cb.addTemplate(page, 0, 0);
            }
        }
        outputStream.flush();
        document.close();
        outputStream.close();
    }

这通常效果很好！但有一段时间，它会将部分页面旋转90度？有人发生过这种事吗？

This usually works great! But once and a while, it's rotating some of the pages by 90 degrees? Anyone ever have this happen?

我正在研究PDF本身，看看正在翻转的内容有什么特别之处。

I am looking into the PDFs themselves to see what is special about the ones that are being flipped.

推荐答案

偶尔会出现错误，因为您使用了错误的方法来连接文档。请阅读本书第6章，您会注意到使用 PdfWriter 连接（或合并）PDF文档是错误的：

There are errors once in a while because you are using the wrong method to concatenate documents. Please read chapter 6 of my book and you'll notice that using PdfWriter to concatenate (or merge) PDF documents is wrong:

• 您完全忽略原始文档中页面的页面大小（您假设它们的大小都是A4），


• 您忽略页面边界，例如裁剪框（如果存在），


• 您忽略存储在页面字典中的旋转值


• 您将丢弃原始文档中存在的所有交互性，依此类推。

• You completely ignore the page size of the pages in the original document (you assume they are all of size A4),
• You ignore page boundaries such as the crop box (if present),
• You ignore the rotation value stored in the page dictionary,
• You throw away all interactivity that is present in the original document, and so on.

使用 PdfCopy 连接PDF，例如参见 FillFlattenMerge2 示例：

Concatenating PDFs is done using PdfCopy, see for instance the FillFlattenMerge2 example:

Document document = new Document();
PdfCopy copy = new PdfSmartCopy(document, new FileOutputStream(dest));
document.open();
PdfReader reader;
String line = br.readLine();
// loop over readers
    // add the PDF to PdfCopy
    reader = new PdfReader(baos.toByteArray());
    copy.addDocument(reader);
    reader.close();
// end loop
document.close();

这本书。

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