Apache PDFBox to rust-pdf-box Migration Guide

This guide helps Java developers familiar with Apache PDFBox transition seamlessly to rust-pdf-box. It highlights conceptual equivalents, architectural differences, memory management benefits, and side-by-side code comparisons.

1. Architectural Philosophy

2. Class & Struct Mapping Cheat Sheet

3. Side-by-Side Code Comparisons

3.1 Creating a Blank Document with Text

Apache PDFBox (Java):

try (PDDocument doc = new PDDocument()) {
    PDPage page = new PDPage(PDRectangle.A4);
    doc.addPage(page);

    try (PDPageContentStream stream = new PDPageContentStream(doc, page)) {
        stream.beginText();
        stream.setFont(PDType1Font.HELVETICA_BOLD, 16);
        stream.newLineAtOffset(50, 750);
        stream.showText("Hello from Apache PDFBox!");
        stream.endText();
    }

    doc.save("output.pdf");
}

rust-pdf-box (Rust):

use rust_pdf_box::prelude::*;

fn main() -> PdfResult<()> {
    let mut doc = PdfDocument::create();
    let page_idx = doc.add_page(PDRectangle::A4);

    let mut stream = PDPageContentStream::new(&mut doc.inner, page_idx, AppendMode::Overwrite)?;
    stream.begin_text()?;
    let font_ref = stream.set_font_type1(&mut doc.inner, page_idx, PDType1Font::HelveticaBold, 16.0)?;
    stream.move_text_position(50.0, 750.0)?;
    stream.show_text("Hello from rust-pdf-box!")?;
    stream.end_text()?;

    doc.save("output.pdf")?;
    Ok(())
}

3.2 Stamping & Watermarking

In Apache PDFBox, adding a background watermark across multiple pages typically requires building a secondary overlay PDF with Overlay or manually opening a content stream in PREPEND mode for every page.

rust-pdf-box Fluent Context API:

#![allow(unused)]
fn main() {
use rust_pdf_box::prelude::*;

let mut doc = PdfDocument::open("document.pdf")?;

// 1. Semi-transparent diagonal watermark across all pages
doc.stamp()
    .pages(PageRange::All)
    .watermark("INTERNAL ONLY", 48.0, Color::rgb(0.9, 0.1, 0.1), 45.0, 0.25)
    .apply(&mut doc.inner)?;

// 2. Official rubber stamp on the first page
doc.stamp()
    .pages(PageRange::Single(1))
    .position(StampPosition::TopRight { margin_x: 36.0, margin_y: 36.0 })
    .rubber_stamp("APPROVED", Some("Audit Team".into()), Color::rgb(0.0, 0.5, 0.2), -10.0)
    .apply(&mut doc.inner)?;

// 3. Running page numbers in the footer
doc.stamp()
    .pages(PageRange::All)
    .footer("Page {page} of {total}", StampPosition::BottomCenter { margin_y: 25.0 }, 10.0, Color::GRAY)
    .apply(&mut doc.inner)?;

doc.save("stamped.pdf")?;
}

3.3 Digital Signatures (PKCS#7 / CMS)

In Apache PDFBox, signing requires implementing SignatureInterface, providing a Java Keystore (KeyStore.getInstance("PKCS12")), wiring BouncyCastle CMS generators, calculating byte ranges manually, and managing temporary files.

rust-pdf-box Pure Rust Digital Signing:

#![allow(unused)]
fn main() {
use rust_pdf_box::prelude::*;

let mut doc = PdfDocument::open("contract.pdf")?;

// Generate self-signed RSA key in memory (or load standard PEM / PKCS#8 key)
let key = SigningKey::generate_self_signed("CN=Techwasti Signer, O=Techwasti Infotech")?;

let signer = Signer::new(key)
    .with_name("Techwasti Infotech")
    .with_reason("Contract Authorization")
    .with_location("Mumbai, India")
    .with_visual_stamp(
        VisualSignature::at_page(1)
            .rect(50.0, 50.0, 260.0, 80.0)
            .title("Digitally Signed Document")
            .detail("Authorized by Techwasti Security\nIntegrity: ISO 32000 Detached PKCS#7")
    );

// Produces signed PDF bytes with cryptographically valid /ByteRange and /Contents
let signed_bytes = doc.sign(signer)?;
std::fs::write("contract_signed.pdf", &signed_bytes)?;

// Cryptographic verification
let report = SignatureVerifier::verify(&signed_bytes)?;
assert!(report.is_valid);
}

3.4 AcroForms & Field Flattening

Apache PDFBox (Java):

PDAcroForm acroForm = doc.getDocumentCatalog().getAcroForm();
if (acroForm != null) {
    PDField field = acroForm.getField("EmployeeName");
    if (field instanceof PDTextField) {
        field.setValue("Alex Johnson");
    }
    acroForm.flatten();
}

rust-pdf-box (Rust):

#![allow(unused)]
fn main() {
use rust_pdf_box::prelude::*;

let mut doc = PdfDocument::open("application_form.pdf")?;

if let Some(mut form) = doc.inner.catalog_mut()?.acro_form()? {
    // Inspect or update fields
    form.set_field_value(&mut doc.inner, "EmployeeName", "Alex Johnson")?;
    form.set_field_value(&mut doc.inner, "Approved", "Yes")?;

    // Burn interactive fields into static visible page graphics
    form.flatten(&mut doc.inner)?;
}

doc.save("application_flattened.pdf")?;
}

4. Key Advantages of rust-pdf-box

1. Performance: No garbage collection pauses, lower memory consumption, and near-instant cold starts (ideal for AWS Lambda, Google Cloud Run, Docker containers, and edge microservices).
2. Safe Concurrency: Immutable PDF documents can be read simultaneously across threads without locks.
3. Ergonomic Facade: Common workflows take 3 lines of code instead of 30 lines of boilerplate.
4. Self-Contained: No external native binaries (libpng, libjpeg, libssl, poppler) required.