Spring Boot Revision — Concept && Coding (Shrayansh Jain)

Structured study notes for every video in Shrayansh's Spring Boot from Basics to Advanced playlist. Each topic has its own NOTES.md with concepts, code examples, configuration, and gotchas.

How to use

# Read the notes for a topic
cat src/main/java/revision/_06_bean_lifecycle/NOTES.md

# Build / run (requires Maven + internet for the first build)
./mvnw spring-boot:run            # if mvnw is added
mvn spring-boot:run               # or system Maven

The pom.xml pulls Spring Boot 3.3 + starters (web, data-jpa, security, aop, actuator, hateoas) + H2 + JJWT — so any code snippet from these notes can be copied into your own @SpringBootApplication class to experiment.

Topic index

Part 1 — Foundations

1. Intro: Spring Boot vs Spring MVC vs Servlets
2. Project setup & Layered architecture
3. Maven & lifecycle
4. Controller-layer annotations
5. Beans, lifecycle & IoC
6. Dependency Injection
7. Bean scopes
8. Dynamically initialised beans (@Value)
9. @ConditionalOnProperty
10. @Profile

Part 2 — Cross-cutting concerns

11. AOP (Aspect-Oriented Programming)
12. @Transactional Part 1
13. @Transactional Part 2 — Declarative vs Programmatic, Propagation
14. @Transactional Part 3 — Isolation levels
15. @Async Part 1 — ThreadPoolExecutor
16. @Async Part 2 — Interview gotchas

Part 3 — Web layer

17. Custom Interceptors & Custom Annotations
18. Filters vs Interceptors
19. HATEOAS
20. ResponseEntity & HTTP response codes
21. Exception handling (@ControllerAdvice, @ExceptionHandler)

Part 4 — JPA (10 parts)

22. JPA Part 1 — JDBC Template
23. JPA Part 2 — Setup, architecture, entity lifecycle
24. JPA Part 3 — L1 caching
25. JPA Part 4 — L2 caching
26. JPA Part 5 — Mapping DTO ↔ Table (@Table, @Column, @Id, @Embeddable)
27. JPA Part 6 — @OneToOne uni & bidirectional
28. JPA Part 7 — @OneToMany, @ManyToOne, @ManyToMany
29. JPA Part 8 — JPQL, Derived queries, N+1, joins, pagination
30. JPA Part 9 — Native query & Criteria API
31. JPA Part 10 — Specification API

Part 5 — Security

32. Web attacks: CSRF / XSS / CORS / SQL Injection
33. Security Part 1 — Architecture & setup
34. Security Part 2 — Multiple users (in-memory, DB)
35. Security Part 3 — Form-based stateful auth
36. Security Part 4 — Basic auth (stateless)
37. JWT explained
38. Security Part 6 — JWT implementation
39. OAuth 2.0 explained
40. Security Part 8 — OAuth implementation
41. Security Part 9 — Method security (@PreAuthorize, @PostAuthorize)

Part 6 — Operations

42. Spring Boot Actuator
43. @ConfigurationProperties