PdfDocument to byte[] using PdfMerger iText7

问题

I've a requirement, where I am generating different pdf' using iText 7.1.11. I am using PdfMerger to merge all pdf's on the fly. I am able to generate pdf successfully at my local system, but the application needs to send bye[] in response. The solution I found here and here . but the problem is PdfMerger does not accept Document object, and I am not sure if i revert my code to use Document instead of PdfDocument will it work or not. Below is the code, with what I tried.

 public static void createPdf(List<String> src, String dest, PageSize pageSize, boolean rotate, String baseUri) throws IOException {
    ConverterProperties properties = new ConverterProperties();
    properties.setBaseUri(baseUri);
    FontProvider fontProvider = new DefaultFontProvider(false,false,true);
    properties.setFontProvider(fontProvider);
    
    /** tried this to make return byte[] in response
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    PdfDocument pdf = new PdfDocument(new PdfWriter(byteArrayOutputStream));
    Document doc = new Document(pdfDoc); **/

    ///////////// Working on Local/////
    PdfWriter writer = new PdfWriter(dest); // 'dest' is local file system path 
    PdfDocument pdf = new PdfDocument(writer);
    PdfMerger merger = new PdfMerger(pdf);

    for (String html : src) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        PdfDocument temp = new PdfDocument(new PdfWriter(baos));
        if(rotate) {
            temp.setDefaultPageSize(pageSize.rotate()); /** Page Size and Orientation */
        } else {
            temp.setDefaultPageSize(pageSize); /** Page Size and Orientation */
        }
        HtmlConverter.convertToPdf(html, temp, properties);
        temp = new PdfDocument(new PdfReader(new ByteArrayInputStream(baos.toByteArray())));
        merger.merge(temp, 1, temp.getNumberOfPages());
        temp.close();
    }
    pdf.close();}

Please help me, as this simple thing seems difficult to achieve

回答1:

This is how you initialize your PdfMerger:

PdfWriter writer = new PdfWriter(dest); // 'dest' is local file system path 
PdfDocument pdf = new PdfDocument(writer);
PdfMerger merger = new PdfMerger(pdf);

I.e. you explicitly write to the local file system and even stress that fact in the comment.

If you want to have the merged PDF in a byte[] at the end, why don't you simply use a ByteArrayOutputStream here (as you claim you have tried a few lines earlier):

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
PdfWriter writer = new PdfWriter(byteArrayOutputStream );
PdfDocument pdf = new PdfDocument(writer);
PdfMerger merger = new PdfMerger(pdf);
...
pdf.close();
byte[] bytes = byteArrayOutputStream.toByteArray();

来源：https://stackoverflow.com/questions/63010524/pdfdocument-to-byte-using-pdfmerger-itext7

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java

arrays

itext

response

itext7