使用PDFBox复制pdf可以像iText一样小吗？ [英] Can duplicating a pdf with PDFBox be small like with iText?

问题描述

我正在阅读PDF并输出包含原始PDF的多个副本的PDF。我通过对 PDFBox 和 iText 。如果我单独复制每个页面，iText会创建一个小得多的输出。

I am reading in a PDF and outputting a PDF with multiple copies of the original PDF in it. I test by doing the same thing for both PDFBox and iText. iText creates a much smaller output if I duplicate each page individually.

问题：还有另一种方法可以在PDFBox中执行此操作，从而产生较小的输出PDF。

The question: Is there another way to do this in PDFBox that results in smaller output PDFs.

对于一个示例输入文件，使用这两个工具为输出生成两个副本：

For one example input file, generating two copies to the output with both tools:

• 原始PDF大小：30K


• PDFBox（v 1.7.1）生成PDF：84K


• iText（v 5.3.4）生成PDF：35K

PDFBox的Java代码（很遗憾对您造成错误处理）。注意它是如何反复读取输入并将其作为一个整体重复：

Java code for PDFBox (sorry to inflict error handling on you). Notice how it reads the input over and over and duplicates it as a whole:

PDFMergerUtility merger = new PDFMergerUtility();
PDDocument workplace = null;
try {
    for (int cnt = 0; cnt < COPIES; ++cnt) {
        PDDocument document = null;
        InputStream stream = null;
        try {
            stream = new FileInputStream(new File(sourceFileName));
            document = PDDocument.load(stream);
            if (workplace == null) {
                workplace = document;
            } else {
                merger.appendDocument(workplace, document);
            }
        } finally {
            if (document != null && document != workplace) {
                document.close();
            }
            if (stream != null) {
                stream.close();
            }
        }
    }

    OutputStream out = null;
    try {
        out = new FileOutputStream(new File(destinationFileName));
        workplace.save(out);
    } finally {
        if (out != null) {
            out.close();
        }
    }
} catch (COSVisitorException e1) {
    e1.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (workplace != null) {
        try {
            workplace.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

使用iText执行此操作的代码。注意它如何逐页加载输入文件并将每个页面传送到输出：

Code to do it with iText. Notice how it loads the input file page by page and transfers each page to the output:

Document document = null;
PdfReader reader = null;
InputStream inputStream = null;
FileOutputStream outputStream = null;
try {
    inputStream = new FileInputStream(new File(sourceFileName));
    outputStream = new FileOutputStream(new File(destinationFileName));
    document = new Document();
    PdfCopy copy = new PdfSmartCopy(document, outputStream);
    document.open();
    reader = new PdfReader(inputStream);
    // loop over the pages in that document
    int pdfPageNo = reader.getNumberOfPages();
    for (int page = 0; page < pdfPageNo;) {
        PdfImportedPage onePage = copy.getImportedPage(reader, ++page);
        // duplicate each page N times
        for (int i = 0; i < COPIES; ++i) {
            copy.addPage(onePage);
        }
    }
    copy.freeReader(reader);
} catch (DocumentException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (reader != null) {
        reader.close();
    }
    if (document != null) {
        document.close();
    }
    try {
        if (inputStream != null) {
            inputStream.close();
        }
        if (outputStream != null) {
            outputStream.close();
        }
    } catch (IOException e) {
        // do nothing
    }
}

两者都被这个包围：

public class Duplicate {

    /** The original PDF file */
    private static final String sourceFileName = "PDF_CI_US2CA.pdf";

    /** The resulting PDF file. */
    private static final String destinationFileName = "itext_output.pdf";
    private static final int COPIES = 2;

    public static void main(String[] args) {
            ...
        }
}

推荐答案

使用以下解决方案，我能够创建一个包含许多重复页面的PDF文件，并且对存储的影响极小。

Using the following solution, I was able to create a PDF file with many duplicate pages and have a minimal impact on storage.

PDDocument samplePdf = null;
try {
    samplePdf = PDDocument.load(PDF_PATH);
    PDPage page = (PDPage) samplePdf.getDocumentCatalog().getAllPages().get(0); 

    for(int i = 0; i < COPIES; i++) {
        samplePdf.importPage(page);
    }

    samplePdf.save(SAVE_PATH); //$NON-NLS-1$

} catch (IOException e) {
    e.printStackTrace();
} catch (COSVisitorException e) {
    e.printStackTrace();
}

在我第一次使用时， samplePdf.addPage （页）但它没有按预期工作。很明显， add 和 import 函数之间存在差异。我将不得不检查源或文档以了解原因。无论如何，这应该可以帮助您使用PDFBox为您的需求设计解决方案。

In my first attempt I used, samplePdf.addPage(page) but it didn't work as expected. So obviously there is a difference between the add and import functions. I'll have to check the source or documentation to see why. Anyway, this should help you devise a solution for your needs with PDFBox.

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