Springboot

Apply these instructions only when the project uses Spring Boot. For Kotlin projects, see kotlin-springboot.

General Instructions

• Make only high confidence suggestions when reviewing code changes.
• Write code with good maintainability practices, including comments on why certain design decisions were made.
• Handle edge cases and write clear exception handling.
• For libraries or external dependencies, mention their usage and purpose in comments.

Spring Boot Instructions

Dependency Injection

• Use constructor injection for all required dependencies.
• Declare dependency fields as private final.

Configuration

• Use application.properties or application.yml for externalized configuration, matching what the project already uses.
• Environment Profiles: Use Spring profiles for different environments (dev, test, prod)
• Configuration Properties: Use @ConfigurationProperties for type-safe configuration binding
• Secrets Management: Externalize secrets using environment variables or secret management systems

Code Organization

• Package Structure: Organize by feature/domain rather than by layer
• Separation of Concerns: Keep controllers thin, services focused, and repositories simple
• Utility Classes: Make utility classes final with private constructors

Service Layer

• Place business logic in @Service-annotated classes.
• Services should be stateless and testable.
• Inject repositories via the constructor.
• Service method signatures should use domain IDs or DTOs, not expose repository entities directly unless necessary.

Logging

• Use SLF4J for all logging (private static final Logger logger = LoggerFactory.getLogger(MyClass.class);).
• Do not use concrete implementations (Logback, Log4j2) or System.out.println() directly.
• Use parameterized logging: logger.info("User {} logged in", userId);.

Security & Input Handling

• Use parameterized queries | Always use Spring Data JPA or NamedParameterJdbcTemplate to prevent SQL injection.
• Validate request bodies and parameters using Bean Validation (@Valid, @NotNull, @Size, etc.) annotations and handle MethodArgumentNotValidException in a @RestControllerAdvice

Build and Verification

• After adding or modifying code, verify the project continues to build successfully.
• If the project uses Maven, run ./mvnw verify (use the wrapper). package skips Failsafe integration tests (*IT).
• If the project uses Gradle, run ./gradlew build (or gradlew.bat build on Windows).
• Ensure all tests pass as part of the build.
• Use package or test only as focused, faster commands, not as the verification gate.

Useful Commands

Gradle Command	Maven Command	Description
./gradlew bootRun	./mvnw spring-boot:run	Run the application.
./gradlew build	./mvnw verify	Build and run all tests.
./gradlew test	./mvnw test	Run tests.
./gradlew bootJar	./mvnw spring-boot:repackage	Package the application as a JAR.
./gradlew bootBuildImage	./mvnw spring-boot:build-image	Package the application as a container image.