Save PDFs to Custom Data Providers in Java

To save a PdfDocument to a custom data provider, use the PdfDocument.saveAs() method.

Custom Data Provider

For full control over the data writing, extend the WritableDataProvider class to provide a custom data sink for saving documents. Here’s an example of an in-memory data provider that uses a byte array for reading and writing data:

// A custom data provider that implements `WritableDataProvider`
// so data can be written to a custom data sink, `pdfData`.
class InMemoryDataProvider implements WritableDataProvider {
    private final List<Byte> pdfData = new ArrayList<>();

    @Override
    public long getSize() {
        return pdfData.size();
    }

    @Nullable
    @Override
    public String getTitle() {
        return "Fake-Title";
    }

    @Override
    public boolean canWrite() {
        // Allowing writing.
        return true;
    }

    @Override
    public boolean startWrite(final WriteMode writeMode) {
        // Remove the current data if rewriting from scratch.
        // If `writeMode` is `WriteMode.APPEND` instead, keep the original content
        // so that write operations are appended to the end of the array. This is important for
        // incremental saving operations.
        if (writeMode == WriteMode.REWRITE) {
            pdfData.clear();
        }

        return true;
    }

    @Override
    public boolean write(final byte[] bytes) {
        for (final byte value : bytes) {
            pdfData.add(value);
        }
        return true;
    }

    @Override
    public boolean finishWrite() {
        // Nothing to do.
        return true;
    }

    @Override
    public @Nullable byte[] read(final long size, final long offset) {
        final List<Byte> subset = new ArrayList<>(pdfData.subList((int) offset, (int) size));
        final byte[] bytes = new byte[(int) size];
        int i = 0;
        for (final Byte b : subset) {
            bytes[i] = b;
            i++;
        }
        return bytes;
    }

    @Override
    public boolean supportsAppending() {
        // You can append onto the string if you want to.
        return true;
    }

    @Override
    public void release() {
        pdfData.clear();
    }
}

You can save to the custom provider using [PdfDocument.saveAs][]:

document.saveAs(new CustomDataProvider(), new DocumentSaveOptions.Builder().build());

Document Save Options

Use DocumentSaveOptions for more control over a document’s saving behavior. The following options are supported:

applyRedactionAnnotations — Applies any redaction annotations present. A full save will be performed, as it isn’t possible to apply redactions incrementally.
flattenAnnotations — Flattens any annotations present. The incremental flag will be ignored when flattening.
forceSave — Forces a save even if there were no modifications.
incremental — Instead of rewriting a PDF, changes will be appended to it. This typically results in a significantly faster save if the document is large, as only the changes are added. It isn’t possible to save incrementally when the flattenAnnotations or applyRedactionsAnnotations options are turned on.

Example

DocumentSaveOptions can be created using the save options Builder. Here’s an example showing how to flatten annotations when saving:

document.save(new DocumentSaveOptions.Builder().flattenAnnotations(true).build());