How to convert iTextPDF Document to Byte Array

I had a similar problem... I'd create the Document and inside the class where I created it, I could save it to File, and it worked great. However, when I tried to return it as a Stream I would get a null value.

The problem was that once the Document was closed (document.close()), it would close the Stream also.

The work-around was to create a ByteArrayOutputStream when I created the Document and have the PdfWriter output to it. I could then do whatever I wanted with the PDF bytes... in my case I converted them to a StreamedContent to send to the user.

Create a variable to hold the bytes:

  private ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

Have the PdfWriter output the data to the byte[] as it creates the document:

  Document document = new Document(PageSize.LETTER, 0.75F, 0.75F, 0.75F, 0.75F);
  PdfWriter.getInstance(document, byteArrayOutputStream);  // Do this BEFORE document.open()

  document.open();
  createPDF(document);  // Whatever function that you use to create your PDF
  document.close();

Once you're done generating the PDF, just get the Bytes and do with them as you will.

  byte[] pdfBytes = byteArrayOutputStream.toByteArray();

I don't know what your reportService class looks like, but this may be a good place to put it.

Hope this helps.

Just updating the answer for the iText 7 version.

private static byte[] createPDF() {
    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    PdfWriter writer = new PdfWriter(byteArrayOutputStream);
    PdfDocument pdfDocument = new PdfDocument(writer);
    Document document = new Document(pdfDocument);

    //Write the file content

    document.close();
    return byteArrayOutputStream.toByteArray();
}

From the comments it appears that it has nothing to do the way PDF is generated at runtime, but instead the way it is stored in the DB. You need to provide that code also.

Here is what I have actually (my test):

The Holder:

import java.io.Serializable;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;



@Entity
public class PDFHolder implements Serializable {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private long id;

@Column(columnDefinition = "LONGBLOB")
private byte[] documentPDF;

public byte[] getDocumentPDF() {
    return documentPDF;
}

public void setDocumentPDF(byte[] documentPDF) {
    this.documentPDF = documentPDF;
}

public long getId() {
    return id;
}

public void setId(long id) {
    this.id = id;
}
}

The Repository, which does the save:

@Repository
public interface PDFHolderRepository extends JpaRepository<PDFHolder, Long> {}

And the actual insert:

private void generateDatabaseRows() {

    try{
        String urlPDF = "http://cetatenie.just.ro/LinkClick.aspx?fileticket=K13DZkoIE2o%3d&tabid=57&mid=593";
        URL url = new URL(urlPDF);

        ByteBuffer byteBufferResponse = this.getAsByteArray(url.openConnection());
        byte [] responseArray = byteBufferResponse.array();
        System.out.println("Size of the PDF : " + responseArray.length);

        // Save it to DB
        PDFHolder pdfHolder = new PDFHolder();
        pdfHolder.setDocumentPDF(responseArray);

        pdfHolderRepository.save(pdfHolder);

    } catch(Exception e){
        e.printStackTrace();
    }
}


private ByteBuffer getAsByteArray(final URLConnection urlConnection) throws IOException {
    final ByteArrayOutputStream tmpOut = new ByteArrayOutputStream();
    final InputStream inputStream = urlConnection.getInputStream();
    final byte[] buf = new byte[1024];
    int len;
    while (true) {
        len = inputStream.read(buf);
        if (len == -1) {
            break;
        }
        tmpOut.write(buf, 0, len);
    }
    tmpOut.close();
    return ByteBuffer.wrap(tmpOut.toByteArray(), 0, tmpOut.size());
}

Of course I have an @Autowired repository in this class:

@Autowired
PDFHolderRepository pdfHolderRepository;