SpringBoot Lab: Learn & Code

Whether you are a beginner building your first RESTful web service or an experienced backend engineer mastering Spring Security 6 and Microservices, SpringBoot Lab gives you hands-on, runnable lessons with instant validation.

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🚀 WHAT YOU WILL LEARN & CODE

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1. CORE SPRING & DEPENDENCY INJECTION

• IoC Container & Component Scanning (@Component, @Service, @Repository)

• Constructor Injection best practices vs @Autowired

• Type-safe configuration with @ConfigurationProperties & profiles (@Profile)

• Bean lifecycle, @Primary, and @Qualifier

2. REST APIs & VALIDATION

• Building controllers with @RestController, @GetMapping, and @PostMapping

• Dynamic parameters with @PathVariable & @RequestParam

• Jakarta Bean Validation (@Valid, @NotNull, @NotBlank, @Email, @Size)

• Centralized exception handling with @RestControllerAdvice & RFC 7807 ProblemDetail

3. SPRING DATA JPA & PERSISTENCE

• Schema mapping with @Entity, @Id, @GeneratedValue, and @Table

• Derived repository queries & custom JPQL using @Query and @Param

• Entity associations (@OneToMany, @ManyToOne) & fixing the N+1 problem with @EntityGraph

• Declarative transaction management with @Transactional and rollback rules

• In-memory and Redis caching with @Cacheable and @CacheEvict

4. SPRING SECURITY 6 & AUTHENTICATION

• Stateless SecurityFilterChain architecture

• Token-based JWT authentication filters (OncePerRequestFilter)

• Endpoint authorization rules with authorizeHttpRequests()

• Method-level security with @PreAuthorize

5. MICROSERVICES & ADVANCED ARCHITECTURE

• Asynchronous execution with @Async & cron scheduling with @Scheduled

• Event-driven architecture using ApplicationEventPublisher and @EventListener

• Microservice fault tolerance using Resilience4j (@CircuitBreaker, @Retry, fallbacks)

• Production observability with Spring Boot Actuator (/actuator/health, /actuator/metrics)

• High-concurrency reactive programming with Spring WebFlux, Mono & Flux

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💻 FULL PROJECT SANDBOX & REST CLIENT

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• Scaffold microservices using the built-in Spring Initializr wizard.

• Edit multi-file Java projects with a dedicated IDE code editor.

• Test your endpoints live with the integrated REST API client (GET, POST, PUT, DELETE).

• Inspect simulated application console logs and build diagnostics in real time.

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🧠 BACKEND JAVA DSA CODING LAB

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Prepare for backend engineering interviews with curated algorithmic problems:

• Transaction Two Sum (HashMap lookups in O(N))

• LRU Cache Service (O(1) get & put with LinkedHashMap)

• Circular Bean Dependency Detector (Graph Cycle Detection & Kahn's Algorithm)

• Sliding Window API Rate Limiter (Queue / Deque throttling)

• Spring URL Route Trie Matcher (Wildcard path resolution)

• Merge K Sorted Service Logs (Min-Heap / PriorityQueue in O(N log K))

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📶 100% OFFLINE PERSISTENCE & PEER COMMUNITY

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• Fully persistent offline Room database—code anywhere without internet.

• Seamless auto-sync updates your progress and forum posts when reconnected.

• Track your learning streak, unlock achievements, and level up your developer rank.

• Ask questions and solve real-world debugging issues with fellow Java developers.

Start coding with SpringBoot Lab today and build production-ready backend applications!