java-spring

Imported from shahboura/agents-opencode (.opencode/skills/java-spring/SKILL.md). Install upstream with npx skills add shahboura/agents-opencode --skill java-spring. Copyright stays with the author (MIT).

What I do

• Enforce Spring Boot layering and dependency injection conventions
• Guide validation, error handling, and security configuration patterns
• Apply testing standards with JUnit 5 and Spring Boot Test

When to use me

Use this when working on Java Spring Boot projects.

Key Rules

• Constructor injection ONLY — never use @Autowired on fields; Spring auto-wires single-constructor beans
• Use Java record types (14+) for all DTOs and request/response objects — not classes with getters/setters
• Layer strictly: Controller (HTTP only) → Service (business logic) → Repository (data access)
• Use Bean Validation annotations (@Valid, @NotBlank, @Email, @Size) at the controller parameter level
• Use @RestControllerAdvice for global exception handling — never catch exceptions in controllers directly
• Extend JpaRepository<T, ID> for data access; use @Query for custom queries, not raw JDBC
• Return Optional<T> from service/repository methods for nullable results — never return null
• Use application.yml (not .properties) for configuration; externalize secrets via ${ENV_VAR} syntax
• Configure Spring Security via SecurityFilterChain bean — not by extending WebSecurityConfigurerAdapter (deprecated)
• Use @Validated on controllers for method-level validation; @Valid on @RequestBody parameters
• Keep controllers thin: no business logic, only HTTP mapping and delegation to services
• Use ResponseEntity with explicit status codes and @ApiResponse annotations (Springdoc/Swagger)
• Background jobs via @Async or Spring ApplicationEvent — not raw threads
• Use a verify-fix-verify loop: run the validation commands below, fix any failures, and rerun until all checks pass

Validation Commands

./mvnw clean compile
./mvnw test