Spring Boot Project

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# Spring Boot Development Instructions (2025)

_Last updated: October 2025_

- Always use the fetch tool to look up the latest Spring Boot documentation: https://spring.io/projects/spring-boot
- Use Spring Boot 3+ with Java 17 or higher
- Follow Spring conventions and use auto-configuration where possible
- Implement dependency injection with constructor injection (preferred over field injection)
- Use Spring Data JPA for database operations with proper entity relationships
- Implement RESTful APIs with Spring Web MVC or Spring WebFlux for reactive applications

**Core Principles:**

- Use annotation-based configuration (@SpringBootApplication, @Service, @Repository, @Controller)
- Implement layered architecture (Controller → Service → Repository)
- Use DTOs for data transfer between layers
- Follow SOLID principles and clean code practices
- Use Lombok to reduce boilerplate code

**Database:**

- Use Spring Data JPA repositories for database access
- Define entities with proper JPA annotations (@Entity, @Table, @Column)
- Implement database migrations with Flyway or Liquibase
- Use pagination and sorting for large datasets
- Implement auditing with @CreatedDate and @LastModifiedDate

**Configuration:**

- Use application.yml or application.properties for configuration
- Implement profiles for different environments (dev, test, prod)
- Use @ConfigurationProperties for type-safe configuration
- Externalize sensitive data with environment variables or Spring Cloud Config
- Use @Value for simple property injection

**Security:**

- Implement Spring Security for authentication and authorization
- Use JWT tokens for stateless authentication in microservices
- Implement method-level security with @PreAuthorize
- Use password encoding with BCryptPasswordEncoder
- Implement CORS configuration for API access

**Testing:**

- Use JUnit 5 and Mockito for unit testing
- Implement integration tests with @SpringBootTest
- Use @WebMvcTest for controller testing
- Use @DataJpaTest for repository testing
- Implement test containers for database integration tests

**Performance:**

- Use caching with @Cacheable and Spring Cache abstraction
- Implement async processing with @Async
- Use connection pooling (HikariCP is default)
- Implement pagination for large datasets
- Use lazy loading for entity relationships

**Microservices:**

- Use Spring Cloud for microservices architecture
- Implement service discovery with Eureka
- Use API Gateway with Spring Cloud Gateway
- Implement circuit breakers with Resilience4j
- Use distributed tracing with Sleuth and Zipkin

**Summary:**

> For all Spring Boot work, always use the fetch tool to look up the latest documentation from https://spring.io/projects/spring-boot. Write clean, maintainable Java code following Spring best practices.