A Java implementation of Google's Agent Payments Protocol (AP2) built on top of a2ajava.

⚠️ Disclaimer: The AP2 protocol is new and still evolving. I have made every effort to validate the implementation details presented here and build a sample java implementation on top of a2ajava; however, some of the technical examples (such as Java code snippets or JSON-RPC message formats) are illustrative and not taken directly from Google’s codebase. The core concepts, goals, and partnerships of AP2 are captured accurately, but developers should always cross-check the latest specifications and the official AP2 GitHub repository for up-to-date implementation details.

AP2Java provides a complete implementation of Google's Agent Payments Protocol (AP2) in Java, allowing Java applications to participate in agent-based payment ecosystems. The project extends the a2ajava library to support payment operations between agents.

This implementation closely follows the patterns in Google's AP2 samples repository:

1. Domain Models: Similar to the Python and Android samples, this Java implementation defines core payment entities like Payment, PaymentRequest, and PaymentResponse.

2. Payment Processing Flow: Follows the same flow as Google's samples:

   • Payment creation
   • Authorization
   • Capture/settlement
   • Refund/cancellation
   • Status checking

3. Agent Integration: Extends a2ajava's AgentCard to add payment capabilities through PaymentEnabledAgentCard.

4. Payment Processor Interface: Provides a standardized interface (PaymentProcessor) that can be implemented for different payment providers.

5. Message Processing: Integrates with a2ajava's messaging system to process payment-related messages between agents.

• Complete Java implementation of the AP2 protocol
• Seamless integration with existing a2ajava applications
• Support for all AP2 payment operations
• Mandate system with Intent, Cart, and Payment mandates
• Verifiable credentials with cryptographic signatures
• Human-present and human-not-present payment flows
• Audit logging with tamper-evident records
• Sample implementations matching Google's AP2 samples
• Comprehensive test coverage

• Java 17 or higher
• Maven 3.6.0 or higher
• a2ajava library

mvn clean install

# Simple payment example
mvn exec:java -Dexec.mainClass="io.github.ap2java.examples.SimplePaymentExample"

# Integration with a2ajava example
mvn exec:java -Dexec.mainClass="io.github.ap2java.examples.AP2IntegrationExample"

// Create payment-enabled agent card
PaymentEnabledAgentCard agentCard = new PaymentEnabledAgentCard();
// ... configure agent card ...

// Create payment processor
PaymentProcessor paymentProcessor = new SamplePaymentProcessor();

// Create AP2 client
AP2Client ap2Client = new AP2Client(paymentProcessor, agentCard);

// Create payment request
PaymentRequest paymentRequest = PaymentRequest.builder()
        .amount(new BigDecimal("50.00"))
        .currencyCode("USD")
        .requestingAgentId("agent-123")
        .receivingAgentId("merchant-456")
        .description("Service payment")
        .build();

// Create payment
PaymentResponse response = ap2Client.createPayment(paymentRequest).get();