Java Payment Gateway Integration
Banks, insurers and large retailers tend to run Java, usually on Spring Boot. Our payment gateway integration in Java ranges from a single checkout call to a standalone payment microservice that several products share. On a typical project we:
- write REST clients for the gateway's order, capture, refund and status endpoints
- generate and verify request signatures, hashes and JWS tokens
- add idempotency keys and safe retry logic, so a network blip never charges a customer twice
- build webhook controllers that verify the signature before touching any data
- keep a transaction ledger in JPA or Hibernate that finance can reconcile against
- cover the flow with JUnit and Mockito tests that run against the gateway sandbox