我正在阅读PDF并输出其中包含原始PDF的多个副本的PDF.我对PDFBox和iText做同样的事情进行测试.如果我分别复制每个页面,iText会创建一个更小的输出.

问题：在PDFBox中还有另一种方法可以实现较小的输出PDF.

对于一个示例输入文件,使用两个工具生成两个副本到输出：

>原始PDF大小：30K
> PDFBox(v 1.7.1)生成的PDF：84K
> iText(v 5.3.4)生成的PDF：35K

PDFBox的Java代码(很抱歉给您造成错误处理).请注意,它是如何反复读取输入并将其整体复制的：

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进行编码的代码.请注意,它是如何逐页加载输入文件并将每页传输到输出的：

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) {
            ...
        }
}

解决方法:

使用以下解决方案,我能够创建具有许多重复页面的PDF文件,并且对存储的影响最小.

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();
}

在我的第一次尝试中,我使用了samplePdf.addPage(page),但是没有按预期工作.因此,显然添加和导入功能之间存在差异.我必须检查源代码或文档以了解原因.无论如何,这应该有助于您使用PDFBox设计解决方案.