WARNING: This application intentionally uses deprecated technologies and patterns for educational purposes. DO NOT USE IN PRODUCTION.

A multi-module Java 8 calculator application built with intentionally deprecated versions of:

• Spring Boot 2.3.12 (deprecated, but Java 8 compatible)
• Lombok 1.18.12 (older version)
• Hibernate 5.4.32 (older version)
• Gradle 6.9.4 (older version)

gradle-calculator/
├── addition-module/           # Addition operations service
├── subtraction-module/        # Subtraction operations service  
├── calculator-core/          # Main application with REST API & database
├── tests/                    # Integration and unit tests
└── build.gradle             # Root Gradle configuration

This application intentionally demonstrates BAD PRACTICES for educational purposes:

• ❌ Field injection with @Autowired (instead of constructor injection)
• ❌ Old-style @SpringBootApplication configuration
• ❌ Manual component scanning
• ❌ Deprecated session management

• ❌ Old Hibernate annotations
• ❌ Manual entity-to-DTO mapping (instead of MapStruct)
• ❌ Raw JPQL queries
• ❌ Old-style repository patterns

• ❌ Manual validation (instead of Bean Validation)
• ❌ Old HTTP servlet patterns
• ❌ Deprecated ResponseEntity usage
• ❌ Manual error handling

• ❌ Manual test setup (instead of @MockBean)
• ❌ Old JUnit patterns
• ❌ Manual MockMvc configuration

• Java 8 (specifically required)
• Gradle 6.9.4 (configured via wrapper)

# Build all modules using wrapper (includes tests)
./gradlew build

# Run the application using wrapper
./gradlew :calculator-core:bootRun

# Run tests only
./gradlew :tests:test

# Or use the provided script
./run-app.sh

# Test the API (in another terminal)
./test-api.sh

• Application: http://localhost:8080
• H2 Console: http://localhost:8080/h2-console
• Health Check: http://localhost:8080/api/calculator/health

# Perform calculation
POST /api/calculator/calculate
Content-Type: application/json

{
  "firstOperand": 10.5,
  "secondOperand": 5.3,
  "operation": "addition",
  "userSession": "optional-session-id"
}

# Direct addition (deprecated)
GET /api/calculator/add?a=10&b=5

# Get calculation history
GET /api/calculator/history?session=your-session&limit=10

Uses H2 in-memory database with deprecated configuration:

• URL: jdbc:h2:mem:calculatordb
• Username: sa
• Password: (empty)

This application is designed for Java 8 and uses deprecated libraries:

This project demonstrates:

1. Legacy Spring Boot patterns from 2020-2021
2. Multi-module Gradle setup with older versions
3. Deprecated Hibernate usage patterns
4. Old-style REST API development
5. Legacy testing approaches

To modernize this application:

1. Upgrade to Java 17+
2. Use Spring Boot 3.x
3. Replace field injection with constructor injection
4. Use Bean Validation instead of manual validation
5. Implement proper error handling
6. Use MapStruct for entity mapping
7. Upgrade testing patterns with modern annotations

# Health check
curl http://localhost:8080/api/calculator/health

# Simple addition
curl "http://localhost:8080/api/calculator/add?a=10&b=5"

# Full calculation
curl -X POST http://localhost:8080/api/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{"firstOperand":15.5,"secondOperand":4.3,"operation":"subtraction"}'

Remember: This is an educational example of deprecated patterns. Use modern Spring Boot practices in real applications! 🎓