Leon Davis

Posted on Dec 5

How to Convert PDF to PDF/A in Java

#java #pdf #pdfa

In daily document management and archiving, ensuring that digital files remain accurately readable decades into the future is a critical concern. Although PDF has become the most common document format, its inherent dynamic elements, external references, and non-embedded fonts can all compromise long-term accessibility.

PDF/A was created to address this issue. As an international standard (ISO 19005), PDF/A requires documents to be “self-contained, independently renderable, and long-term readable,” making it widely adopted in government, archives, finance, healthcare, and legal fields where compliance is essential.

This article highlights the core value of PDF/A and provides a solution for converting PDF to PDF/A using Java and the Spire.PDF for Java library.

1. Why Convert to PDF/A?

Regular PDFs, due to their flexibility and complex features, carry the following risks:

Unembedded fonts: May cause garbled text or layout issues when opened
Dynamic elements like transparency, layers, scripts: Rendering may vary across software
External references or links: Cannot guarantee long-term availability
Inconsistent color spaces: May appear differently on various devices

PDF/A ensures future readability through strict limitations and standardization. Core requirements include:

All fonts must be embedded
JavaScript, encryption, and external references are disallowed
XMP metadata must be included
Color spaces must be clearly defined
Compatibility requirements are consistent across devices

Common PDF/A versions:

PDF/A-1a / 1b: Earliest version based on PDF 1.4; 1a requires accessibility structure, 1b only ensures visual consistency
PDF/A-2a / 2b: Based on PDF 1.7, supports transparency, JPEG2000, layers, and modern features
PDF/A-3a / 3b: Allows embedding arbitrary external files, such as XML or Word originals

In practice, PDF/A-1b and PDF/A-2b are the most commonly used targets.

2. Why Choose Spire.PDF for PDF/A Conversion?

In the Java ecosystem, few libraries support PDF/A conversion. Spire.PDF for Java provides a direct, simple, and reliable API for converting PDF → PDF/A without manually embedding fonts, adjusting color spaces, or complex validation.

Advantages of Spire.PDF:

Direct conversion using PdfStandardsConverter
Automatically handles font embedding, XMP metadata generation, transparency flattening
Supports main PDF/A standards: PDF/A-1b, PDF/A-2b, PDF/A-3b
Suitable for batch processing, backend services, and archiving systems

3. Using Java and Spire.PDF to Convert PDF to PDF/A (Complete Example)

3.1 Add Maven Dependencies

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>

<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.pdf</artifactId>
        <version>11.11.11</version>
    </dependency>
</dependencies>

3.2 Java Code Example for PDF to PDF/A Conversion

The following code demonstrates how to convert a PDF to PDF/A-1b in Java:

import com.spire.pdf.conversion.PdfStandardsConverter;

public class ConvertToPdfA {
    public static void main(String[] args) {

        // Input PDF file
        String input = "input.pdf";

        // Output PDF/A file
        String output = "output_pdfa1b.pdf";

        try {
            // Create PdfStandardsConverter instance
            PdfStandardsConverter converter = new PdfStandardsConverter(input);

            // Convert to PDF/A-1b
            converter.toPdfA1B(output);

            System.out.println("Conversion complete: PDF saved as PDF/A-1b");

        } catch (Exception e) {
            System.out.println("Conversion failed: " + e.getMessage());
        }
    }
}

3.3 Converting to Other PDF/A Standards

Simply replace the conversion method:

// PDF/A-1a
converter.toPdfA1A("output_1a.pdf");

// PDF/A-2a / 2b
converter.toPdfA2A("output_2a.pdf");
converter.toPdfA2B("output_2b.pdf");

// PDF/A-3a / 3b
converter.toPdfA3A("output_3a.pdf");
converter.toPdfA3B("output_3b.pdf");

3.4 Common Issues and Best Practices

Even though Spire.PDF handles most compliance automatically, consider the following:

Choose the Right PDF/A Version

PDF/A-1b: Most common archival standard, ensures long-term preservation
PDF/A-2b: Supports transparency and modern image formats
PDF/A-3b: Suitable for embedding XML, Excel, or Word originals

Avoid Editing After Conversion

Any post-conversion edits (e.g., annotations, watermarks) may break PDF/A compliance. Recommended workflow:

Complete all edits first
Convert to PDF/A as the final step

Batch Processing Large Files

Spire.PDF supports:

Stream-based PDF loading (reduces memory usage)
Multi-threaded conversion (ideal for backend servers)
Useful for electronic archive systems and batch processing platforms.

Font Compatibility

To ensure fonts are properly embedded:

Prefer commonly used fonts
Install all necessary business fonts on the server

Conclusion

PDF/A is a key standard for ensuring long-term readability, verifiability, and archiving of digital documents. Compared to the complex process of manually validating and fixing PDFs, Spire.PDF provides Java developers with a simple, efficient solution for PDF to PDF/A conversion.

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