Java Spring Framework

Review the core object-oriented programming concepts in Java — classes, interfaces, inheritance, and polymorphism — that Spring relies on heavily.

Understand how Java annotations work and how reflection allows frameworks like Spring to inspect and configure your code at runtime.

Learn how to manage dependencies, build lifecycle, and project structure using Maven or Gradle, the standard build tools for Spring projects.

Understand the IoC principle and how the Spring ApplicationContext manages object creation, configuration, and lifecycle for you.

Learn constructor, setter, and field injection patterns and why DI leads to loosely coupled, testable code.

Explore how Spring beans are defined, their lifecycle callbacks, and the different scopes (singleton, prototype, request, session) that control their lifespan.

Configure Spring applications using @Configuration classes and @Bean methods instead of XML, the modern and preferred approach.

Understand the legacy XML-based configuration approach, which you will encounter in older Spring codebases.

Learn how @Component, @Service, @Repository, and @Controller let Spring automatically discover and register your beans.

Use SpEL to inject dynamic values, evaluate expressions, and reference bean properties in configuration.

Understand how Spring Boot uses opinionated defaults and auto-configuration to eliminate boilerplate and get applications running quickly.

Learn how starter POMs bundle compatible dependencies so you can add capabilities (web, data, security) with a single dependency.

Configure your application using application.yml/properties files and switch between environments (dev, staging, prod) using Spring profiles.

Expose production-ready endpoints for health checks, metrics, and application info to monitor your running application.

Build HTTP APIs using @RestController, request mapping annotations, and understand the DispatcherServlet request lifecycle.

Handle path variables, query parameters, request bodies, and validate input using Bean Validation annotations.

Implement global and controller-level exception handling with @ExceptionHandler and @ControllerAdvice to return consistent error responses.

Explore the reactive, non-blocking alternative to Spring MVC for building high-throughput applications using Project Reactor.

Use Spring Data JPA to interact with relational databases through repository interfaces, eliminating boilerplate data access code.

Understand declarative transaction management with @Transactional, isolation levels, propagation behaviors, and rollback rules.

Access MongoDB, Redis, and other NoSQL stores through Spring Data's consistent repository abstraction.

Configure Spring Security's filter chain to authenticate users and authorize access to endpoints using roles and authorities.

Implement token-based authentication with JWT and integrate with OAuth2 providers for modern, stateless security.

Secure individual service methods using @PreAuthorize, @PostAuthorize, and other expression-based access control annotations.

Write isolated unit tests for Spring components by mocking dependencies with Mockito and running tests outside the Spring context.

Write integration tests that boot the full or sliced Spring context to verify that components work together correctly.

Use Testcontainers to spin up real databases in Docker during tests, avoiding the pitfalls of in-memory database differences.

Implement cross-cutting concerns like logging, auditing, and performance monitoring using Spring AOP aspects and pointcuts.

Add transparent caching to service methods with @Cacheable and integrate with providers like Redis or Caffeine.

Build event-driven architectures using Spring's messaging abstractions for Apache Kafka or RabbitMQ.

Decompose applications into microservices using Spring Cloud for service discovery, configuration management, circuit breakers, and API gateways.