in28minutes/master-spring-and-spring-boot

1. This repository is a teaching monorepo, not a single product. It contains many independent sample applications grouped by topic and course stage. Most folders are self-contained Spring Boot or React projects with their own build files, source tree, resources, and tests.

2. The top-level layout is organized by learning area: Spring Framework, Spring Boot, JPA/Hibernate, Web MVC, REST APIs, Full Stack React + Spring Boot, Testing, Security, AOP, Build tools, Docker, and AWS. The .md, .zip, and step-by-step files are instructional artifacts that document incremental code evolution rather than runtime components.

3. The Spring Framework examples in 01-spring/learn-spring-framework-01 and learn-spring-framework-02 focus on the IoC container, bean wiring, and configuration styles. These projects center around simple domain classes like GamingConsole, MarioGame, PacmanGame, SuperContraGame, and runners such as GameRunner to demonstrate dependency injection, bean scopes, lazy initialization, lifecycle callbacks, XML config, and CDI-style concepts.

4. The Spring Boot basics in 02-springboot show the transition from manual Spring wiring to Boot auto-configuration and profiles. This app includes a small Course domain and controllers like CourseController and CurrencyConfigurationController, with application.properties plus profile-specific overrides in application-dev.properties and application-prod.properties.

5. The JPA/Hibernate introduction in 03-jpa-getting-started evolves persistence from JDBC to JPA and Spring Data JPA. The core domain is Course, and the repositories are split by persistence style: course/jdbc, course/jpa, and course/springdatajpa. schema.sql seeds the database, and the command-line runner exercises the repository layer at startup.

6. The Spring MVC web application in 11-web-application is a server-rendered app using JSP views. Requests flow from controllers like SayHelloController, WelcomeController, TodoController, and TodoControllerJpa to service/repository layers (TodoService, TodoRepository), then back to JSPs under WEB-INF/jsp. It also includes Spring Security configuration and static SQL seed data, so the architecture combines MVC, session-backed login flow, and database-backed todos.

7. The REST API projects in 12-rest-api, 91-aws/02-rest-api-mysql, and 13-full-stack/02-rest-api expose JSON endpoints rather than HTML views. They include HelloWorldController, user and todo resources, exception handling, filtering, versioning, and i18n. The domain layer includes User, Post, and Todo, with DAO-style in-memory services alongside JPA repositories such as UserRepository, PostRepository, and TodoRepository.

8. Security is a major cross-cutting boundary. Across the REST and web apps you see basic auth, JWT, and form/login security configurations (SpringSecurityConfiguration, BasicAuthenticationSecurityConfiguration, JwtSecurityConfig, OauthSecurityConfiguration). These configurations sit at the edge of the app and protect controller/resource layers before requests reach business or persistence code.

9. The full-stack architecture in 13-full-stack and 91-aws/04-frontend-react splits the system into two deployable parts: a React frontend and a Spring Boot backend. The frontend lives in todo-app/src/components/... and uses ApiClient, AuthenticationApiService, TodoApiService, and AuthContext to manage API calls and auth state. The backend provides todo, hello-world, and authentication endpoints, with CORS and token handling to support browser-based calls.

10. The React side is structured as a component-based UI layer with feature folders for todo, counter, and learning examples. The todo feature contains pages and shared layout components (HeaderComponent, FooterComponent, LoginComponent, WelcomeComponent, TodoComponent, ListTodosComponent, LogoutComponent) plus a small API client layer. State is shared through React context for authentication, which is the main boundary between UI and server interaction.

11. Persistence in the later applications is intentionally varied to show architectural tradeoffs: in-memory DAO services, Spring JDBC, JPA/Hibernate, and Spring Data JPA. The repository layer is the stable boundary, while the service and controller/resource layers stay mostly the same as persistence changes underneath.

12. The repo also contains cross-cutting infrastructure demos: 51-junit for unit testing, 52-mockito for mocking/stubbing, 73-spring-aop for aspects and pointcuts, 81-maven and 82-gradle for build tooling, 83-docker for containerization, and 91-aws for deployment scenarios. These are separate learning modules, not runtime dependencies of a single application.

13. For architecture diagrams, the most accurate mental model is a set of parallel example systems rather than one monolith:

• Spring core samples: bean container and dependency injection

• Web MVC app: browser → controller → service → repository → JSP

• REST apps: client → REST controller/resource → service/repository → JSON

• Full stack app: React UI → REST API with auth/security → persistence

• Supporting modules: tests, AOP, build, Docker, AWS

14. The primary external systems that materially affect the architecture are H2/MySQL databases, the browser/React runtime, Spring Security auth flows, and deployment/runtime targets like Docker and AWS. Everything else in the repo is oriented around demonstrating how code moves across those boundaries.