java-springboot

When to Use

• Developing Spring Boot applications
• Need best practices for Spring Boot
• Configuring Spring Boot projects
• Working with Spring framework components

Core Principles

1. Constructor Injection — Always use it for testability. Never @Autowired on fields.
2. DTOs — Never expose JPA entities to the API layer. Use records or projection interfaces.
3. Package by Feature — Group by domain (order/, user/), not by layer (controller/, service/).
4. Validation — Use Bean Validation (@Valid, @NotBlank) on request DTOs.
5. Transactions — Keep them short and at the service layer with @Transactional.
6. Logging — Use parameterized logging ({}), never string concatenation.
7. Security — Never hardcode secrets. Use env vars and @ConfigurationProperties.
8. Testing — Use the narrowest test slice that gives you confidence.
9. Configuration — Externalize everything via application.yml and @ConfigurationProperties.
10. Monitoring — Add Actuator and health checks to every service.

Reference Index

Topic	Reference
Build tool, starters, package structure	references/project-setup.md
Constructor injection, Lombok, stereotypes	references/dependency-injection.md
application.yml, @ConfigurationProperties, profiles, secrets	references/configuration.md
REST controllers, DTOs, validation, exception handler	references/web-layer.md
Business logic, @Transactional	references/service-layer.md
Repositories, queries, projections	references/data-layer.md
SLF4J logging patterns	references/logging.md
Spring Security, JWT, password encoding	references/security.md
Async, caching, API versioning, pagination	references/advanced.md
Actuator, health indicators	references/monitoring.md
Test slice quick reference	references/testing.md

Commands

# Run Spring Boot application
mvn spring-boot:run

# Run with specific profile
mvn spring-boot:run -Dspring-boot.run.profiles=dev

# Build project
mvn clean package

# Run tests
mvn test

# Run specific test
mvn test -Dtest=OrderServiceTest

Testing

For comprehensive testing guidance (test slices, MockMvcTester, Testcontainers, AssertJ), see the java-springboot-testing skill.

Quick Reference

Test Type	Annotation	Use For
Unit	@ExtendWith(MockitoExtension.class)	Service logic
Web	@WebMvcTest	Controllers
Data	@DataJpaTest	Repositories
Integration	@SpringBootTest	Full flow
Slice	@RestClientTest	REST clients

Context7 Integration

When you need up-to-date information on Spring Boot:

1. Resolve the libraryId — Use context7_resolve-library-id with:

   • libraryName: "spring boot" or "spring framework"
   • query: what you're going to do (e.g., "configuration properties", "custom health check")

2. Query the docs — Use context7_query-docs with:

   • libraryId: the ID from the previous step (e.g., "/spring/spring-boot")
   • query: your specific question

Before answering about Spring Boot APIs, configurations, or best practices, consult Context7 to get up-to-date information.

Resources

• Spring Boot Documentation
• Spring Framework Documentation
• Spring Security Documentation