尝试使用 iText7 合并合并 pdf，但是当我打开最终合并的 pdf 时，它说无法加载 pdf 文档

Question

I'm creating two ByteArrayOutputStream using itext7 PdfWriter, and then merging them in one pdf using merger but when I try to open final merged pdf it says failed to load.

@GetMapping(value = "/customers",
            produces = MediaType.APPLICATION_PDF_VALUE)
public ResponseEntity<InputStreamResource> customersReport() throws IOException {

    ByteArrayOutputStream out = new ByteArrayOutputStream();
    PdfDocument pdf = new PdfDocument(new PdfWriter(out));
    Document document = new Document(pdf);
    Paragraph p = new Paragraph("AAAAAAAAA");
    document.add(p);
    document.close();    

    ByteArrayOutputStream out1 = new ByteArrayOutputStream();
    PdfDocument pdf1 = new PdfDocument(new PdfWriter(out1));
    Document document1 = new Document(pdf1);
    Paragraph p1 = new Paragraph("123456A");
    document1.add(p1);
    document1.close();

    ByteArrayOutputStream outfinal = new ByteArrayOutputStream();
    PdfDocument pdfDoc = new PdfDocument(new PdfWriter(outfinal));
    PdfMerger merger = new PdfMerger(pdfDoc);

    PdfDocument pdf2 = new PdfDocument(new PdfReader(new ByteArrayInputStream(out.toByteArray())));
    merger.merge(pdf2,1,pdf2.getNumberOfPages());

    PdfDocument pdf3 = new PdfDocument(new PdfReader(new ByteArrayInputStream(out1.toByteArray())));
    merger.merge(pdf3,1,pdf3.getNumberOfPages());

    ByteArrayInputStream bis = new ByteArrayInputStream(outfinal.toByteArray());

    HttpHeaders headers = new HttpHeaders();
    headers.add("Content-Disposition", "inline; filename=customers.pdf");

    return ResponseEntity
            .ok()
            .headers(headers)
            .contentType(MediaType.APPLICATION_PDF)
            .body(new InputStreamResource(bis));
}

Answer 1

You have to close the merger

merger.close();

before using its output in

ByteArrayInputStream bis = new ByteArrayInputStream(outfinal.toByteArray());

because only during closing the pdf file is completed.