Spring and Spring Boot Labs

Comprehensive hands-on exercises for learning Spring Boot fundamentals, from basic web applications to database persistence patterns.

Prerequisites

• Java 17 or later (Spring Boot 3.x requires Java 17+)
• Spring Boot 3.5.3 (current version)
• Gradle 8.14.2 (latest stable)
• IDE with Spring Boot support (IntelliJ IDEA, Spring Tool Suite, or VS Code)

Lab Materials

📚 labs.md - Comprehensive Basic Labs

Foundation labs covering Spring Boot fundamentals from web development to database persistence.

🚀 advanced-labs.md - Enterprise Development Labs

Advanced labs building a complete shopping application with enterprise patterns. Updated to match the final implementation exactly - students can copy from the solution when needed:

• Progressive entity design with JPA validation and Lombok
• Spring Data repositories with custom queries and indexes
• REST API development with modern DTOs and full CRUD operations
• Global exception handling with RFC 7807 ProblemDetail
• Transaction management and comprehensive testing strategies
• YAML configuration with profile separation using ---

Project Structure

This repository contains three independent Spring Boot projects that demonstrate different aspects of the framework:

📁 demo - Basic Spring Boot Web Application

• Package: com.kousenit.demo
• Purpose: Introduction to Spring Boot web development
• Features:
  • Thymeleaf templating
  • REST controllers with JSON responses
  • Unit and integration testing
  • Basic web forms and static content

📁 restclient - External API Integration

• Package: com.kousenit.restclient
• Purpose: Consuming external REST APIs
• Features:
  • Modern RestClient for synchronous calls
  • WebClient for reactive/asynchronous calls
  • JSON Placeholder API integration (no API keys required)
  • NASA Open Data API examples
  • Comprehensive error handling

📁 persistence - Database Access Patterns

• Package: com.kousenit.persistence
• Purpose: Various approaches to data persistence
• Features:
  • Modern JdbcClient (Spring Boot 3.2+)
  • Traditional JdbcTemplate
  • JPA with Hibernate
  • Spring Data JPA repositories
  • H2 in-memory database

📁 shopping - Enterprise Shopping Application (NEW)

• Package: com.kousenit.shopping
• Purpose: Complete enterprise application demonstrating advanced patterns
• Features:
  • JPA entities with comprehensive validation and Lombok
  • Database indexes for performance optimization
  • Spring Data JPA with custom queries and sophisticated repository patterns
  • Service layer with transaction management and business logic
  • REST API with modern DTOs and full CRUD operations
  • Global exception handling with RFC 7807 ProblemDetail responses
  • YAML configuration with test profile isolation
  • Sample data initialization with profile-aware CommandLineRunner
  • Comprehensive test suite with modern @MockitoBean annotations
  • Production-ready logging and monitoring endpoints

Quick Start

Build All Projects

# From the root directory
./gradlew build

# Or build individual projects
cd demo && ./gradlew build
cd restclient && ./gradlew build
cd persistence && ./gradlew build
cd shopping && ./gradlew build

Run Applications

# Demo application (port 8080)
cd demo && ./gradlew bootRun

# REST client examples
cd restclient && ./gradlew bootRun

# Persistence examples with H2 console
cd persistence && ./gradlew bootRun

# Shopping application (port 8080)
cd shopping && ./gradlew bootRun

Run Tests

# All tests
./gradlew test

# Specific project tests
cd demo && ./gradlew test
cd restclient && ./gradlew test
cd persistence && ./gradlew test
cd shopping && ./gradlew test

Key Learning Topics

Modern Spring Boot Features

• Spring Boot 3.5.3 with Java 17+ features
• Records for immutable data classes and DTOs
• Text blocks for readable SQL and JSON
• RestClient as the modern replacement for RestTemplate
• JdbcClient as the modern alternative to JdbcTemplate
• @MockitoBean replacing deprecated @MockBean
• Lombok for reducing boilerplate with proper IDE integration
• YAML configuration with --- profile separation
• RFC 7807 ProblemDetail for standardized error responses

Web Development

• RESTful web services with @RestController
• Server-side rendering with Thymeleaf
• Static content and form handling
• HTTP client integration patterns

Data Access

• Modern JDBC: JdbcClient and JdbcTemplate patterns
• JPA Entity Mapping: Annotations and relationship management
• Spring Data JPA: Repository pattern with automatic query generation
• Database Configuration: Multi-environment setup with profiles
• Connection Management: H2 for development, PostgreSQL for production

Configuration Management

• Property Injection: @Value annotation for external configuration
• Profile-Specific Properties: application-{profile}.yml files
• Environment Variables: Secure configuration for production
• Feature Toggles: Profile-based conditional bean creation

Testing

• Unit Testing: JUnit 5 with comprehensive assertions and modern patterns
• Integration Testing: @SpringBootTest with profile activation and test isolation
• Web Layer Testing: @WebMvcTest with MockMVC for REST API testing
• Service Layer Testing: @MockitoBean for dependency mocking
• Entity Validation Testing: Bean validation with constraint violation testing
• Reactive Testing: StepVerifier for WebClient flows
• Database Testing: Repository testing with @DataJpaTest
• Profile Testing: @ActiveProfiles for environment-specific tests

API Integrations

JSON Placeholder (No API Key Required)

• Users API: Complex nested JSON structures with address and company data
• Posts API: Complete CRUD operations (GET, POST, DELETE)
• Configuration: Externalized URLs and timeouts with @Value annotation
• Demonstrates: Modern record classes, full HTTP method support, sync/async patterns, robust error handling

NASA Open Data

• Astronauts in Space: Real-time space station crew data
• Demonstrates: WebClient usage, reactive programming

Development Environment

Recommended IDEs

• IntelliJ IDEA Ultimate - Full Spring Boot support
• Spring Tool Suite - Eclipse-based with Spring tools
• VS Code - With Spring Boot extensions

Database Access

Development Profile (default):

• H2 Console: http://localhost:8080/h2-console
• JDBC URL: jdbc:h2:mem:shopping (or project-specific name)
• Username: sa
• Password: (empty)

Profile Switching:

# Run with different profiles
./gradlew bootRun --args='--spring.profiles.active=dev'    # H2 (default)
./gradlew bootRun --args='--spring.profiles.active=test'   # H2 optimized for testing
./gradlew bootRun --args='--spring.profiles.active=prod'   # PostgreSQL via Testcontainers

# Shopping application with debug logging
cd shopping && ./gradlew bootRun --args='--spring.profiles.active=dev'

Shopping Application Endpoints:

• H2 Console: http://localhost:8080/h2-console
• Health Check: http://localhost:8080/actuator/health
• API Documentation: http://localhost:8080/api/v1/products

Optional Requirements

Docker Desktop (for advanced testing):

• Required for PostgreSQL Testcontainers integration
• Production profile tests will be skipped if Docker is unavailable
• All core functionality works without Docker using H2 database

Modern Java Features Used

• Records - Immutable data classes for JSON mapping
• Text Blocks - Readable multi-line SQL queries
• Pattern Matching - Enhanced switch expressions
• Local Variable Type Inference - var keyword usage
• Optional - Null-safe API responses

Contributing

This project follows modern Spring Boot best practices:

• Package structure: com.kousenit.*
• Java 17+ features throughout
• Comprehensive test coverage
• Modern dependency management
• Clean separation of concerns

License

See LICENSE file for details.