Enterprise Inventory & Order Management System

A production-grade Spring Boot enterprise application demonstrating core Java/JEE concepts including Dependency Injection, Transaction Management, AOP, Spring Batch, and REST APIs.

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Tech Stack

Layer	Technology
Framework	Spring Boot 3.2.5
Language	Java 17
ORM / Data Access	Hibernate / JPA (Spring Data JPA)
Batch Processing	Spring Batch
AOP	Spring AOP (AspectJ)
Database	H2 (dev) / MySQL (prod)
Testing	JUnit 5 + Mockito
Build Tool	Maven
Boilerplate Reduction	Lombok

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Key Concepts Demonstrated

1. Dependency Injection & IoC

Spring's IoC container manages all beans. Constructor injection is used throughout (preferred over field injection).

@Service
@RequiredArgsConstructor  // Lombok generates constructor — Spring injects dependencies
public class ProductServiceImpl implements ProductService {
    private final ProductRepository productRepository; // injected by Spring
}

2. Transaction Management

@Transactional ensures atomic operations — if any step fails, everything rolls back.

@Transactional(rollbackFor = Exception.class)
public OrderDTO placeOrder(OrderDTO orderDTO) {
    // Step 1: decrease stock
    // Step 2: create order record
    // If Step 2 fails → Step 1 is ROLLED BACK automatically
}

3. Aspect-Oriented Programming (AOP)

A single LoggingAspect class handles logging, execution timing, and exception tracking for all service methods — without touching service code.

@Around("serviceLayer()")
public Object measureExecutionTime(ProceedingJoinPoint pjp) throws Throwable {
    long start = System.currentTimeMillis();
    Object result = pjp.proceed();
    log.info("Executed in {} ms", System.currentTimeMillis() - start);
    return result;
}

4. Spring Batch — Chunk-Oriented Processing

Processes inventory records in configurable chunks, each with its own transaction.

ItemReader → reads low-stock products from DB
ItemProcessor → validates and flags critical items
ItemWriter → writes batch report
Chunk size: 10 items per transaction

5. Test-Driven Development (TDD)

8 unit tests with JUnit 5 + Mockito covering success, failure, and edge cases.

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Project Structure

src/
├── main/java/com/akanksha/inventory/
│   ├── InventoryApplication.java       # Entry point
│   ├── aspect/
│   │   └── LoggingAspect.java          # AOP — centralised logging & timing
│   ├── batch/
│   │   └── InventoryBatchConfig.java   # Spring Batch job configuration
│   ├── controller/
│   │   ├── ProductController.java      # REST API endpoints for products
│   │   └── OrderController.java        # REST API endpoints for orders + batch trigger
│   ├── dto/
│   │   ├── ProductDTO.java
│   │   └── OrderDTO.java
│   ├── entity/
│   │   ├── Product.java                # JPA Entity with lifecycle hooks
│   │   └── Order.java                  # JPA Entity with ManyToOne relationship
│   ├── exception/
│   │   ├── GlobalExceptionHandler.java # Centralised error handling
│   │   └── ResourceNotFoundException.java
│   ├── repository/
│   │   ├── ProductRepository.java      # JPA Repository with custom JPQL queries
│   │   └── OrderRepository.java
│   └── service/
│       ├── ProductService.java         # Interface (IoC principle)
│       ├── ProductServiceImpl.java     # Implementation with @Transactional
│       └── OrderService.java           # Atomic order placement
└── test/java/com/akanksha/inventory/
    └── service/
        └── ProductServiceTest.java     # 8 JUnit 5 + Mockito unit tests

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Getting Started

Prerequisites

• Java 17+
• Maven 3.8+

Run (No Database Setup Needed)

# Clone the repository
git clone https://github.com/AkankshaKesarkar/inventory-management-system.git
cd inventory-management-system

# Build and run (uses H2 in-memory DB automatically)
mvn spring-boot:run

Run Tests

mvn test

Access

URL	Description
http://localhost:8080/api/products	Product REST API
http://localhost:8080/api/orders	Order REST API
http://localhost:8080/h2-console	H2 DB Console (dev only)

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REST API Reference

Products

Method	Endpoint	Description
POST	/api/products	Create a product
GET	/api/products	Get all products
GET	/api/products/{id}	Get product by ID
GET	/api/products/category/{cat}	Filter by category
GET	/api/products/low-stock?threshold=10	Get low-stock products
PUT	/api/products/{id}	Update product
DELETE	/api/products/{id}	Delete product
GET	/api/products/inventory-value	Total inventory value

Orders

Method	Endpoint	Description
POST	/api/orders	Place an order (atomic)
GET	/api/orders	Get all orders
GET	/api/orders/{id}	Get order by ID
PUT	/api/orders/{id}/cancel	Cancel an order
POST	/api/orders/batch/run-inventory-report	Trigger batch job

Sample Request — Create Product

POST /api/products
{
  "name": "Laptop",
  "category": "Electronics",
  "price": 75000.00,
  "stockQuantity": 50
}

Sample Request — Place Order

POST /api/orders
{
  "customerName": "Akanksha Kesarkar",
  "productId": 1,
  "quantity": 2
}

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Author

Akanksha Ramchandra Kesarkar
B.E. Computer Science & Engineering | 2024
📧 akankshakesarkar5@gmail.com
🔗 LinkedIn