Spring on dplabs — Software Engineering & Technology Consultancy

Spring Boot Dependency Injection Without Losing Your Architecture

Mon, 21 Jul 2025 00:00:00 +0000

Spring’s dependency injection container is one of the most mature and capable DI frameworks available. It’s also capable of enabling architectures that are deeply coupled to Spring internals, impossible to test without a full Spring context, and opaque about their dependencies.

The patterns that produce good Spring Boot architectures are not complicated. They require deliberate choices about when to use Spring and when to step back from it.

Constructor Injection Is Non-Negotiable

Spring supports three injection mechanisms: constructor, setter, and field injection. Field injection (@Autowired on a field) is the most common and the worst.

Modern Spring Boot Architecture: Beyond the Three-Layer Application

Mon, 02 Dec 2024 00:00:00 +0000

The three-layer architecture — controllers, services, repositories — is how most Spring Boot tutorials present application structure. It’s a reasonable starting point. It’s also a pattern that breaks down as applications grow.

The problems are predictable: services become God classes with hundreds of methods, repository calls leak into controllers, domain logic spreads across multiple layers, and changing anything requires understanding the entire application at once. The layered architecture doesn’t enforce boundaries — it suggests them. Suggestions decay under deadline pressure.