Spring Core – Muscle Memory Repository

This repository is a comprehensive, task-driven implementation of all fundamental and advanced concepts in the Spring Core module of the Spring Boot Mastery Learning Plan.

It focuses on building muscle memory through hands-on coding, ensuring practical command of every concept rather than theoretical familiarity.

All tasks were provided by ChatGPT (as per the structured Spring Boot Mastery Plan), and the author implemented each task entirely on their own, following the given instructions and then submitting the code for review and feedback.

This Repository is just of record of learning and hands-on work done by the author, there is no other significant meaning to this.

📘 Project Overview

Repository Name: spring-core-muscle-memory

Language: Java 21

Framework: Spring Boot 3.x

Build Tool: Maven

IDE Used: IntelliJ IDEA

Author: Chandra Sekhar

This repository covers 10 structured topics from the official SPRING CORE.txt learning plan, each broken into incremental tasks designed for real-world understanding.

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🧩 Topics & Coverage

Topic No.	Topic Name	Description
1	Introduction to Spring	Conceptual overview of Spring Framework, Inversion of Control, and Dependency Injection.
2	IoC and Dependency Injection	Demonstrates constructor, setter, and field-based DI using XML, JavaConfig, and annotations.
3	Bean Lifecycle	Explores @PostConstruct, @PreDestroy, InitializingBean, DisposableBean, and custom init/destroy methods.
4	Bean Scopes	Demonstrates singleton vs prototype scopes and prototype injection scenarios.
5	Component Scanning	Uses @Component, @Service, @Repository, and @Controller stereotypes with multi-package scanning.
6	Autowiring in Spring	Covers constructor, setter, and field injection, @Qualifier, optional dependencies, and resolution rules.
7	Java-Based Configuration	Explores JavaConfig classes, @Bean methods, hybrid configs, and scopes.
8	@Value Injection and Property Sources	Demonstrates property injection from files and system env using @Value, @PropertySource, and SpEL.
9	Spring Profiles	Implements environment-specific beans and property files for dev and prod profiles.
10	Spring Expression Language (SpEL)	Demonstrates expressions for arithmetic, logical operations, bean access, and environment integration.

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🧠 Learning Objective

The goal of this project is to develop instinctive fluency in Spring Core concepts such as:

• IoC Container and Bean Creation
• Dependency Injection mechanisms
• Bean Lifecycle callbacks
• Bean Scopes and Proxies
• Component Scanning and Stereotype annotations
• Autowiring and Qualifier strategies
• JavaConfig and PropertySource usage
• Profile-based environment configuration
• Spring Expression Language integration

Each task is self-contained and can be run individually for focused experimentation.

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🧮 Project Structure

spring-core-muscle-memory/
 ├── src/
 │   ├── main/
 │   │   ├── java/
 │   │   │   ├── topic1_introduction/
 │   │   │   ├── topic2_ioc_di/
 │   │   │   ├── topic3_bean_lifecycle/
 │   │   │   ├── topic4_scopes/
 │   │   │   ├── topic5_component_scanning/
 │   │   │   ├── topic6_autowired/
 │   │   │   ├── topic7_java_config/
 │   │   │   ├── topic8_value_injection/
 │   │   │   ├── topic9_profiles/
 │   │   │   └── topic10_spel/
 │   │   └── resources/
 │   │       ├── application.properties
 │   │       ├── application-dev.properties
 │   │       ├── application-prod.properties
 │   │       └── topic2_ioc_di/... (XML configs)
 ├── pom.xml
 └── .gitignore

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▶️ Running Individual Tasks

Each task has its own main() class ending with Demo or Application.

Run from IntelliJ IDEA

1. Open the project.
2. Navigate to any task (e.g. topic4_scopes/task1/SingletonScopeDemo.java).
3. Right-click → Run ‘SingletonScopeDemo.main()’.

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🧩 Git Commit Convention

Each commit follows the convention:

feat: implement <topic>-<task> – <short description>

Examples

feat: implement topic2-task3 – Combined Java & XML Config Demo
feat: implement topic4-task1 – Singleton Bean Scope Demo

This ensures a clean, traceable learning timeline.

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⚙️ Prerequisites

• Java 21+
• Maven 3.9+
• IntelliJ IDEA or VS Code
• Spring Boot 3.x dependencies (managed via Maven)

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🖯️ Next Phase

→ Proceed to the Spring AOP Module, continuing the same task-driven structure. Each subsequent repository builds directly on the foundation established here.

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Author: Chandra Sekhar Learning Journey: Spring Boot Mastery Plan Mentorship & Tasks Provided By ChatGPT (OpenAI)