Learn Spring Boot REST API Development
Organize a Spring Boot service
Spring Boot simplifies application setup and provides conventions for common web services. Dependency injection supplies a class with the collaborators it needs, making dependencies visible and easier to replace in tests. Constructor injection is explicit and supports immutable fields.
A common layered structure places HTTP handling in a controller, business rules in a service and persistence operations behind a repository. The layers should have clear responsibilities: controllers translate the web contract, services coordinate behavior and repositories handle data access. This is a useful starting point, not a requirement to create needless classes for every line of code.
Design a predictable REST contract
Model endpoints around resources and use HTTP methods consistently: GET to read, POST to create, PUT or PATCH to update and DELETE to remove. Return status codes that communicate the result, such as a success response for a completed request or a not-found response when a resource does not exist. Use request and response DTOs to avoid accidentally exposing internal persistence details.
Validate incoming data at the boundary. A title may be required and have a maximum length; an identifier should be parsed and checked. Validation errors should explain which fields need attention without exposing stack traces or internal implementation details.
Handle errors and test behavior
Centralized exception handling can map known application errors to a consistent JSON shape. Do not catch every exception and report success: unexpected failures should remain visible in logs and receive an appropriate server error response. Never return credentials, tokens or sensitive data in an error message.
Test service rules independently, then add web-layer tests for routes, validation and status codes. API clients such as Postman are useful for manual exploration, but automated tests make contracts repeatable and protect against regressions.
Keep the API understandable
Document endpoint purpose, required fields and response examples. Use pagination when collections can grow, and make filtering behavior explicit. When the React frontend is added, it should be able to rely on the API contract rather than guess response behavior.