How to Retrieve Document Metadata in Java

Ever needed to quickly check a document’s page count before processing it? Or extract form field data from hundreds of PDFs without opening each one manually? You’re not alone—extracting document metadata programmatically is one of those tasks that sounds simple until you actually try to do it.

Here’s the good news: with the right Java library, you can pull document properties, signatures, form fields, and more from virtually any file format in just a few lines of code. Whether you’re building a document management system, automating compliance checks, or just need to batch-process files, this guide will show you exactly how to retrieve document metadata in Java.

What you’ll learn:

  • Setting up a Java document processing library (takes about 5 minutes)
  • Extracting basic properties like format, size, and page count
  • Pulling detailed information from signatures, form fields, barcodes, and QR codes
  • Handling common issues and performance considerations
  • Real-world use cases where metadata extraction saves hours of manual work

Let’s start by understanding why you’d want to extract document metadata in the first place.

Why Extract Document Metadata? (Real-World Use Cases)

Before we dive into code, let’s talk about when this capability actually matters. Here are some scenarios where programmatic metadata extraction becomes essential:

1. Automated Document Validation You’re building a system that processes invoices, contracts, or forms. Before running expensive OCR or analysis, you need to verify that documents meet basic requirements—like having exactly 3 pages, containing specific form fields, or including a digital signature.

2. Document Management Systems Your users upload thousands of files monthly. You need to automatically categorize them, generate previews, and display properties (file size, page count, creation date) without manually opening each one.

3. Compliance & Audit Trails Financial services, healthcare, and legal industries require detailed logs of who signed what and when. Extracting signature metadata programmatically ensures you can verify document authenticity at scale.

4. Batch Processing Workflows You’re migrating legacy documents to a new system. You need to extract metadata from 50,000+ files to populate a database, identify duplicates, or split multi-page documents based on properties.

5. Form Data Extraction Your company receives signed application forms as PDFs. Instead of manual data entry, you can automatically extract form field values and pipe them directly into your database.

Now that you know why this matters, let’s get your environment set up.

Prerequisites

Before we get our hands dirty with code, make sure you have:

  • Java Development Kit (JDK): Version 8 or higher (though Java 11+ is recommended for better performance)
  • IDE: IntelliJ IDEA, Eclipse, or NetBeans—whatever you’re comfortable with
  • Build Tool: Maven or Gradle for dependency management
  • Basic Java Knowledge: You should understand objects, methods, and exception handling

Pro Tip: If you’re working with large documents or processing files in bulk, make sure your JVM has enough heap space allocated. You can set this with -Xmx2g (for 2GB) when running your application.

Setting Up GroupDocs.Signature for Java

Setting up your environment is straightforward, but getting it right from the start will save you headaches later. GroupDocs.Signature is a robust Java library that handles not just signatures, but comprehensive document metadata extraction across 50+ file formats.

Maven Setup

Add this dependency to your pom.xml file:

<dependency>
    <groupId>com.groupdocs</groupId>
    <artifactId>groupdocs-signature</artifactId>
    <version>23.12</version>
</dependency>

Gradle Setup

Or include this in your build.gradle file:

implementation 'com.groupdocs:groupdocs-signature:23.12'

Where to Download:

Quick Start Tip: The trial version works perfectly for learning and small projects. It includes a watermark on output, but for metadata extraction (which is what we’re doing), this doesn’t matter since we’re just reading, not writing.

Basic Initialization

Once you’ve added the dependency, here’s how to initialize the library:

import com.groupdocs.signature.Signature;

public class InitializeGroupDocs {
    public static void main(String[] args) {
        String filePath = "YOUR_DOCUMENT_DIRECTORY/sample_signed_multi";
        Signature signature = new Signature(filePath);
    }
}

What’s happening here? The Signature class is your main entry point. Despite its name, it handles all document operations—not just signatures. Think of it as your document reader that unlocks all the metadata inside.

Common Mistake to Avoid: Make sure your file path uses forward slashes (/) or escaped backslashes (\\) on Windows. Java doesn’t like unescaped Windows paths like C:\Documents\file.pdf.

Implementation Guide

Now for the fun part—let’s extract some actual metadata. We’ll start simple and progressively dive deeper into what you can pull from documents.

Extracting Basic Document Properties

This is your bread-and-butter operation. Before you do anything complex with a document, you often need to know: What format is this? How many pages does it have? How big is the file?

When to Use This

  • Before processing: Check if a document meets size or page count requirements
  • For user interfaces: Display file information in document management dashboards
  • During validation: Ensure uploaded files match expected formats

Step 1: Initialize Signature Object

Create an instance of Signature by passing the document path:

final Signature signature = new Signature("YOUR_DOCUMENT_DIRECTORY/sample_signed_multi");

File Format Support: This works with PDFs, Word documents (DOC, DOCX), Excel spreadsheets (XLS, XLSX), PowerPoint presentations, images (JPG, PNG), and 40+ other formats. You don’t need to specify the format—the library detects it automatically.

Step 2: Retrieve Document Information

Use the getDocumentInfo() method to obtain details about the document:

import com.groupdocs.signature.domain.IDocumentInfo;

IDocumentInfo documentInfo = signature.getDocumentInfo();

What you’re getting: The IDocumentInfo object is essentially a metadata container. It holds everything from basic file properties to detailed signature information.

Step 3: Print Document Properties

Extract and display essential properties such as format, extension, size, and page count:

System.out.println("Document properties:");
System.out.println(" - Format : " + documentInfo.getFileType().getFileFormat());
System.out.println(" - Extension : " + documentInfo.getFileType().getExtension());
System.out.println(" - Size : " + documentInfo.getSize());
System.out.println(" - Page Count : " + documentInfo.getPageCount());

// Iterate through each page to display its properties
import com.groupdocs.signature.domain.PageInfo;

for (PageInfo pageInfo : documentInfo.getPages()) {
    System.out.println(" - Page-" + pageInfo.getPageNumber() + ", Width: " + pageInfo.getWidth() + ", Height: " + pageInfo.getHeight());
}

What This Output Tells You:

  • Format: The document type (e.g., “Portable Document Format”)
  • Extension: File extension (e.g., “.pdf”)
  • Size: File size in bytes (you’ll want to convert this to KB/MB for display)
  • Page Count: Total number of pages
  • Per-Page Dimensions: Width and height (useful for determining if pages have custom sizes)

Practical Example: Let’s say you’re processing invoice PDFs. You know valid invoices should be exactly 2 pages. You can quickly filter out invalid submissions:

if (documentInfo.getPageCount() != 2) {
    System.out.println("Invalid invoice: Expected 2 pages, got " + documentInfo.getPageCount());
    return; // Skip processing
}

Performance Note: Calling getDocumentInfo() is fast—typically under 100ms even for large PDFs—because it only reads metadata headers, not the entire file content.

Extracting Form Field Information

Forms are everywhere—job applications, tax documents, medical records. If your documents contain fillable form fields, you can extract their names, types, and values programmatically.

When to Use This

  • Automated data entry: Pull form values into databases without manual typing
  • Form validation: Verify that required fields are filled before processing
  • Template analysis: Understand the structure of unfamiliar form documents

Step 1: Access Form Fields

Utilize the getFormFields() method to fetch information about each form field:

import com.groupdocs.signature.domain.signatures.formfield.FormFieldSignature;

for (FormFieldSignature formField : documentInfo.getFormFields()) {
    System.out.println(" - Type #" + formField.getType() + ": Name: " + formField.getName() + ", Value: " + formField.getValue());
}

Understanding Form Field Types:

  • Text fields: Single-line or multi-line text inputs
  • Check boxes: Boolean yes/no values
  • Radio buttons: Single selection from multiple options
  • Dropdown lists: Predefined option selections
  • Digital signature fields: Placeholders for signatures (we’ll cover these separately)

Real-World Scenario: Imagine you’re processing job applications. Each PDF has fields like “Full Name”, “Email”, “Phone”, and “Years of Experience”. Instead of reading each application manually, you extract these values and populate your applicant tracking system automatically.

Gotcha: Some PDFs have form fields that look filled but actually contain empty values. Always check for null or empty strings when processing form data to avoid surprises.

Extracting Text Signatures

Text signatures are those typed names, titles, or labels that appear in documents—things like “Approved by John Smith, CFO” or “Confidential”. They’re different from actual handwritten or digital signatures.

When to Use This

  • Compliance checks: Verify that required approval text exists
  • Document classification: Identify documents by signature markers
  • Audit trails: Extract who approved what and when (if timestamps are included)

Step 1: Retrieve Text Signatures

Call the getTextSignatures() method to gather text signature details:

import com.groupdocs.signature.domain.signatures.TextSignature;

for (TextSignature textSignature : documentInfo.getTextSignatures()) {
    System.out.println(" - #" + textSignature.getSignatureId() + ": Text: " + textSignature.getText() + ", Location: " + textSignature.getLeft() + "x" + textSignature.getTop() + ". Size: " + textSignature.getWidth() + "x" + textSignature.getHeight());
}

What You Get:

  • Signature ID: Unique identifier for each text signature
  • Text content: The actual text string
  • Position: X/Y coordinates (left, top) where the signature appears
  • Dimensions: Width and height of the text box

Why Position Matters: If you need to verify that a signature appears in a specific location (like the bottom-right corner of page 1), you can check the coordinates programmatically. This is useful for template validation.

Pro Tip: Text signatures are often confused with regular text. The difference? Text signatures are explicitly added as signature objects, not just typed into the document. If you’re not seeing expected results, the text might be regular content rather than a signature element.

Extracting Image Signatures

Image signatures are typically company logos, stamps, or scanned handwritten signatures embedded in documents. These are different from background images—they’re specifically added as signature elements.

When to Use This

  • Logo verification: Ensure corporate logos appear on official documents
  • Stamp authentication: Verify that official stamps or seals are present
  • Visual signature validation: Confirm handwritten signature images exist

Step 1: Fetch Image Signature Details

Use the getImageSignatures() method to retrieve image-related information:

import com.groupdocs.signature.domain.signatures.ImageSignature;

for (ImageSignature imageSignature : documentInfo.getImageSignatures()) {
    System.out.println(" - #" + imageSignature.getSignatureId() + ": Size: " + imageSignature.getSize() + " bytes, Format: " + imageSignature.getFormat());
}

What This Tells You:

  • Signature ID: Unique identifier
  • Size: Image file size in bytes (useful for quality checks)
  • Format: Image format (PNG, JPG, etc.)

Practical Use Case: Let’s say your company requires all contracts to have the corporate logo as an image signature. You can validate this during upload:

if (documentInfo.getImageSignatures().isEmpty()) {
    System.out.println("Warning: No company logo found in contract");
}

Important Note: This method only detects images added as signatures, not regular images in the document. If someone just inserts a logo as a picture, it won’t show up here.

Extracting Digital Signatures

Digital signatures are the gold standard for document authenticity. They use cryptographic keys to prove that a document hasn’t been tampered with since signing. This is what you use for legal contracts, financial documents, and anything requiring non-repudiation.

When to Use This

  • Legal verification: Confirm document authenticity in court or disputes
  • Compliance requirements: Meet regulatory standards for signed documents
  • Security audits: Verify that documents come from trusted sources

Step 1: Access Digital Signature Details

Invoke the getDigitalSignatures() method:

import com.groupdocs.signature.domain.signatures.DigitalSignature;

for (DigitalSignature digitalSignature : documentInfo.getDigitalSignatures()) {
    System.out.println(" - #" + digitalSignature.getSignatureId());
}

What You Can Extract:

  • Signature ID: Unique identifier for each digital signature
  • Certificate details: Information about the signing certificate (issuer, validity dates)
  • Signer information: Name and email of the person who signed
  • Timestamp: When the document was signed

Security Note: Just because a document has a digital signature doesn’t mean it’s valid. The signature might be expired, revoked, or from an untrusted source. Always validate digital signatures against trusted certificate authorities in production systems.

Common Pitfall: Digital signatures are only as secure as the private key used to create them. If you’re building a system that relies on digital signatures for legal purposes, consult with security experts about proper key management.

Extracting Barcode Signatures

Barcodes in documents serve as machine-readable identifiers. They’re commonly used for tracking, inventory management, and automated data capture. Think shipping labels, product packaging, or ID badges.

When to Use This

  • Inventory tracking: Extract product codes from scanned labels
  • Document routing: Use barcodes to automatically sort documents
  • Data validation: Verify that barcodes contain expected information

Step 1: Retrieve Barcode Signature Details

Utilize the getBarcodeSignatures() method:

import com.groupdocs.signature.domain.signatures.BarcodeSignature;

for (BarcodeSignature barcodeSignature : documentInfo.getBarcodeSignatures()) {
    System.out.println(" - #" + barcodeSignature.getSignatureId() + ": Type: " + barcodeSignature.getEncodeType().getTypeName());
}

Barcode Types You Might Encounter:

  • Code128: High-density barcode for alphanumeric data
  • QR Code: 2D barcode that can store URLs, contact info, etc.
  • EAN-13: Standard product barcodes (UPC codes)
  • Code39: Simple barcode often used in logistics

Real-World Example: You’re processing shipping documents. Each document has a barcode containing the tracking number. Instead of manually typing tracking numbers into your system, you extract them programmatically:

for (BarcodeSignature barcode : documentInfo.getBarcodeSignatures()) {
    if (barcode.getEncodeType().getTypeName().equals("Code128")) {
        String trackingNumber = barcode.getText();
        System.out.println("Tracking number: " + trackingNumber);
    }
}

Performance Tip: Barcode extraction can be slower than other metadata operations because it requires image processing. If you’re processing thousands of documents, consider extracting barcodes only when needed rather than from every document.

Common Issues & Solutions

Even with clean code, you’ll run into hiccups. Here are the most common problems and how to fix them fast.

Issue 1: File Not Found or Access Denied

Symptom: FileNotFoundException or access permission errors

Solution:

  • Verify the file path is correct and uses proper path separators
  • Check file permissions—your Java process needs read access
  • Make sure the file isn’t open in another application (especially on Windows)
File docFile = new File(filePath);
if (!docFile.exists()) {
    System.err.println("File not found: " + filePath);
} else if (!docFile.canRead()) {
    System.err.println("Cannot read file: " + filePath);
}

Issue 2: Unsupported File Format

Symptom: Exceptions when trying to process certain files

Solution:

  • Check the supported formats list before processing
  • Validate file extensions before attempting to open documents
  • Have a fallback handler for unsupported formats
String extension = filePath.substring(filePath.lastIndexOf('.'));
if (!extension.matches("\\.(pdf|docx|xlsx)")) {
    System.out.println("Unsupported format: " + extension);
    return;
}

Issue 3: Out of Memory Errors with Large Files

Symptom: OutOfMemoryError when processing large documents

Solution:

  • Increase JVM heap size: -Xmx4g for 4GB of memory
  • Process documents in batches rather than all at once
  • Close Signature objects properly to release resources
try (Signature signature = new Signature(filePath)) {
    // Process document
    IDocumentInfo info = signature.getDocumentInfo();
    // Use the info...
} // Signature automatically closed here

Issue 4: Empty Metadata Collections

Symptom: Methods return empty lists when you expect data

Solution:

  • Not all documents contain all types of metadata (e.g., unsigned documents won’t have signatures)
  • Some metadata might be stored differently than expected (text as regular content vs. text signature)
  • Verify the document actually contains what you’re looking for by opening it manually first
if (documentInfo.getFormFields().isEmpty()) {
    System.out.println("No form fields found - this might be a regular PDF, not a form");
}

Best Practices for Production Use

Once you’ve got the basics down, here’s how to make your implementation robust for real-world use.

1. Always Use Try-With-Resources

The Signature object holds system resources. Always close it properly:

try (Signature signature = new Signature(filePath)) {
    IDocumentInfo info = signature.getDocumentInfo();
    // Your code here
} catch (Exception e) {
    System.err.println("Error processing document: " + e.getMessage());
}

2. Implement Proper Error Handling

Don’t let exceptions crash your application. Wrap operations in try-catch blocks and log errors for debugging:

try {
    IDocumentInfo info = signature.getDocumentInfo();
} catch (Exception e) {
    logger.error("Failed to retrieve document info for: " + filePath, e);
    // Handle gracefully—maybe skip this file or alert the user
}

3. Cache Metadata for Frequently Accessed Documents

If you’re repeatedly checking the same documents, cache the metadata instead of re-reading files:

private Map<String, IDocumentInfo> metadataCache = new HashMap<>();

public IDocumentInfo getDocumentInfo(String filePath) {
    return metadataCache.computeIfAbsent(filePath, path -> {
        try (Signature sig = new Signature(path)) {
            return sig.getDocumentInfo();
        }
    });
}

4. Validate Input Before Processing

Always validate files meet your requirements before heavy processing:

public boolean isValidInvoice(String filePath) {
    try (Signature sig = new Signature(filePath)) {
        IDocumentInfo info = sig.getDocumentInfo();
        return info.getPageCount() == 2 
            && info.getFileType().getExtension().equals(".pdf")
            && info.getSize() < 5_000_000; // 5MB limit
    }
}

5. Handle Large-Scale Processing Efficiently

If you’re processing thousands of files, use parallel processing with proper resource management:

List<String> files = Arrays.asList(/* your file paths */);
ExecutorService executor = Executors.newFixedThreadPool(4);

files.forEach(filePath -> executor.submit(() -> {
    try (Signature sig = new Signature(filePath)) {
        IDocumentInfo info = sig.getDocumentInfo();
        // Process metadata
    } catch (Exception e) {
        logger.error("Error processing: " + filePath, e);
    }
}));

executor.shutdown();

6. Log Metadata Extraction for Audit Trails

For compliance-heavy applications, log what metadata was extracted and when:

logger.info("Extracted metadata for: {} - Pages: {}, Size: {} bytes, Signatures: {}", 
    filePath, 
    info.getPageCount(), 
    info.getSize(),
    info.getDigitalSignatures().size());

Conclusion

You now have a solid foundation for extracting document metadata in Java. Whether you’re validating uploaded files, building document management systems, or automating compliance checks, you can programmatically access file properties, signatures, form fields, and more without opening files manually.

Key Takeaways:

  • Start with basic properties (format, size, page count) before diving into complex metadata
  • Always handle exceptions and validate inputs—not every document contains every type of metadata
  • Use try-with-resources to properly manage system resources
  • Cache metadata when possible to improve performance
  • Consider your use case: do you need real-time extraction or batch processing?

Next Steps:

  • Explore adding signatures programmatically (not just reading them)
  • Implement document validation workflows using metadata rules
  • Build a document classification system based on extracted properties
  • Integrate metadata extraction into existing document management systems

Want to go deeper? Check out the GroupDocs documentation for advanced features like signature verification, custom metadata extraction, and format-specific operations.