Employee Management System

A modern REST API for employee management built with Spring Boot 3.2.12 and Java 21.

🚀 Features

• Full CRUD Operations - Create, Read, Update, Delete employees
• Input Validation - Jakarta Bean Validation with detailed error messages
• Filter by Status - Query employees by their status
• Global Exception Handling - Structured error responses
• MySQL Database - JPA/Hibernate with auto-schema generation
• CORS Support - Configured for cross-origin requests
• Hot Reload - Spring Boot DevTools for development

📋 Tech Stack

Technology	Version
Java	21 (LTS)
Spring Boot	3.2.12
Jakarta EE	3.x
Hibernate	6.4.10
MySQL	8.x
Maven	3.9.x

🎯 Recent Upgrades

This project was recently upgraded from Java 17 to Java 21 with the following improvements:

✅ Java 21 LTS - Latest long-term support version
✅ Spring Boot 3.2.12 - Modern Spring Framework 6.x
✅ Jakarta EE Migration - Migrated from javax.* to jakarta.*
✅ Enhanced Validation - Bean validation with @Valid and @NonNull
✅ Improved Error Handling - Global exception handler with structured responses
✅ Type Safety - LocalDate for dates, wrapper types for optional fields
✅ Better REST API - ResponseEntity with proper HTTP status codes

🛠️ Prerequisites

Before running this application, ensure you have:

• JDK 21 or later installed
• MySQL 8.x running on localhost:3306
• Maven 3.9.x (or use included Maven wrapper)
• Database: emp_db

⚡ Quick Start

1. Clone the Repository

git clone https://github.com/Palenzo/Java-Employee-Management-Website.git
cd Java-Employee-Management-Website

2. Setup MySQL Database

CREATE DATABASE IF NOT EXISTS emp_db;

Or using command line:

mysql -u root -p -e "CREATE DATABASE IF NOT EXISTS emp_db;"

3. Configure Database (Optional)

Edit src/main/resources/application.properties if needed:

spring.datasource.url=jdbc:mysql://localhost:3306/emp_db
spring.datasource.username=root
spring.datasource.password=YOUR_PASSWORD

4. Run the Application

Using Maven Wrapper (Recommended):

./mvnw spring-boot:run

Or build and run JAR:

./mvnw clean package
java -jar target/crud-0.0.1-SNAPSHOT.jar

The application will start on http://localhost:8080

📡 API Endpoints

Base URL: http://localhost:8080/api/employee

Method	Endpoint	Description	Request Body
POST	/api/employee	Create new employee	JSON (see below)
GET	/api/employee	Get all employees	-
GET	/api/employee?status=1	Filter by status	-
GET	/api/employee/{id}	Get employee by ID	-
PUT	/api/employee/{id}	Update employee	JSON (partial)
DELETE	/api/employee/{id}	Delete employee	-

📝 Request/Response Examples

Create Employee (POST)

curl -X POST http://localhost:8080/api/employee \
  -H "Content-Type: application/json" \
  -d '{
    "name": "John Doe",
    "doj": "2025-01-15",
    "status": 1,
    "salary": 50000.0
  }'

Response (201 Created):

{
  "id": 1,
  "name": "John Doe",
  "doj": "2025-01-15",
  "status": 1,
  "salary": 50000.0
}

Get All Employees (GET)

curl http://localhost:8080/api/employee

Response (200 OK):

[
  {
    "id": 1,
    "name": "John Doe",
    "doj": "2025-01-15",
    "status": 1,
    "salary": 50000.0
  }
]

Get Employee by ID (GET)

curl http://localhost:8080/api/employee/1

Update Employee (PUT)

curl -X PUT http://localhost:8080/api/employee/1 \
  -H "Content-Type: application/json" \
  -d '{
    "salary": 55000.0
  }'

Delete Employee (DELETE)

curl -X DELETE http://localhost:8080/api/employee/1

Response (200 OK):

{
  "message": "Employee deleted successfully"
}

🧪 Testing with PowerShell

Create Employee

Invoke-RestMethod -Uri "http://localhost:8080/api/employee" `
  -Method Post `
  -ContentType "application/json" `
  -Body '{"name":"Jane Smith","doj":"2025-10-16","status":1,"salary":60000.0}'

Get All Employees

Invoke-RestMethod -Uri "http://localhost:8080/api/employee" -Method Get

Filter by Status

Invoke-RestMethod -Uri "http://localhost:8080/api/employee?status=1" -Method Get

Update Employee

Invoke-RestMethod -Uri "http://localhost:8080/api/employee/1" `
  -Method Put `
  -ContentType "application/json" `
  -Body '{"salary":65000.0}'

Delete Employee

Invoke-RestMethod -Uri "http://localhost:8080/api/employee/1" -Method Delete

🔍 Validation Rules

The API validates incoming requests:

Field	Rule	Error Message
name	Required, not blank	"name is required"
doj	Not in future	"date of joining cannot be in the future"
salary	Optional	-
status	Optional	-

Validation Error Response (400 Bad Request):

{
  "name": "name is required",
  "doj": "date of joining cannot be in the future"
}

🗂️ Project Structure

src/
├── main/
│   ├── java/com/employee/crud/
│   │   ├── CrudApplication.java          # Main application
│   │   ├── controller/
│   │   │   ├── EmployeeController.java   # REST endpoints
│   │   │   ├── GlobalExceptionHandler.java  # Error handling
│   │   │   └── WebConfig.java            # CORS configuration
│   │   ├── entity/
│   │   │   └── Employee.java             # JPA entity
│   │   ├── repository/
│   │   │   └── EmployeeRepository.java   # Data access
│   │   └── service/
│   │       ├── EmployeeService.java      # Service interface
│   │       └── EmployeeServiceImpl.java  # Business logic
│   └── resources/
│       └── application.properties        # Configuration
└── test/
    └── java/com/employee/crud/
        └── CrudApplicationTests.java     # Unit tests

🐛 Troubleshooting

MySQL Connection Failed

Error: Communications link failure

Solution:

1. Verify MySQL is running: Get-Service -Name "*mysql*"
2. Start MySQL: Start-Service MySQL
3. Check credentials in application.properties
4. Ensure database emp_db exists

Port 8080 Already in Use

Error: Port 8080 is already in use

Solution:

# Find process using port 8080
netstat -ano | findstr :8080

# Kill the process (replace PID)
Stop-Process -Id <PID> -Force

JDK Version Issues

Error: Unsupported class file major version

Solution: Ensure you're using JDK 21 or later:

java -version

If using an older JDK, install JDK 21 and set JAVA_HOME:

$env:JAVA_HOME = 'C:\Program Files\Java\jdk-21'

🔧 Development

Running Tests

./mvnw test

Building Without Tests

./mvnw clean package -DskipTests

Hot Reload (DevTools)

The project includes Spring Boot DevTools. Changes to Java files will auto-reload during development.

Database Schema

Hibernate auto-generates the schema (spring.jpa.hibernate.ddl-auto=update). The employee table structure:

Column	Type	Constraints
id	BIGINT	PRIMARY KEY, AUTO_INCREMENT
name	VARCHAR(255)	NOT NULL
doj	DATE	-
status	INT	-
salary	FLOAT	-

🌐 CORS Configuration

CORS is enabled for:

• Origin: http://localhost (configurable in WebConfig.java)
• Methods: GET, POST, PUT, DELETE, OPTIONS
• Headers: All
• Credentials: Enabled

📦 Maven Dependencies

Key dependencies:

• spring-boot-starter-web - REST API support
• spring-boot-starter-data-jpa - JPA/Hibernate
• spring-boot-starter-validation - Bean validation
• mysql-connector-j - MySQL driver
• spring-boot-devtools - Hot reload
• spring-boot-starter-test - Testing support

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

📄 License

This project is open source and available under the MIT License.

👤 Author

Palenzo

• GitHub: @Palenzo
• Repository: Java-Employee-Management-Website

📞 Support

If you encounter any issues or have questions:

1. Check the Troubleshooting section
2. Open an issue on GitHub
3. Review existing issues for solutions

🎓 Learning Resources

• Spring Boot Documentation
• Jakarta EE Documentation
• Java 21 Documentation
• MySQL Documentation

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Built with ❤️ using Java 21 and Spring Boot 3.2.12