📖 Blog Application

A full-featured Blog Application built with Spring Boot, Spring Security, and JWT.
It supports user authentication, role-based access (ADMIN & USER), posts, comments, and pagination.

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📂 Project Structure

blog-app/
│── src/main/java/com/security/blog/
│   ├── config/          # Security configurations
│   ├── controller/      # REST controllers
│   ├── dto/             # Data Transfer Objects (LoginDto, RegisterDto, etc.)
│   ├── entity/          # Entities (Post, Comment, User)
│   ├── exception/       # Custom exceptions & handlers
│   ├── repository/      # Spring Data JPA repositories
│   ├── security/        # JWT classes (Filter, TokenProvider, EntryPoint)
│   ├── service/         # Business logic layer
│   └── BlogAppApplication # Main Spring Boot application
│
└── src/main/resources/
    ├── application.properties # Database & JWT configurations

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⚙️ Installation & Setup

1. Clone the repository

   git clone https://github.com/VaradM-17/my-blog-app.git
   cd my-blog-app/blog-app

2. Configure Database
   Open src/main/resources/application.properties and update it with your DB credentials:

   spring.datasource.url=jdbc:mysql://localhost:3306/blog_app
   spring.datasource.username=root
   spring.datasource.password=yourpassword
   spring.jpa.hibernate.ddl-auto=update
   
   # JWT properties
   app.jwt-secret=your_jwt_secret_key
   app.jwt-expiration-milliseconds=604800000

3. Build & Run the application

   mvn spring-boot:run

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🚀 Features

• 🔐 Authentication & Authorization using Spring Security + JWT
• 👥 Role-based access (ADMIN, USER)
• 📝 Posts & Comments (One-to-Many relationship)
• 📑 Pagination & Sorting for posts
• 📦 DTOs for clean API requests/responses
• ⚠️ Exception handling
• 🗄️ MySQL Database with JPA & Hibernate

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🔑 API Endpoints

🔐 Authentication

Endpoint	Method	Access	Description
/api/auth/register	POST	Public	Register a new user
/api/auth/login	POST	Public	Login and receive JWT token

📝 Posts

Endpoint	Method	Access	Description
/api/posts	POST	ADMIN	Create a new post
/api/posts	GET	USER, ADMIN	Get all posts (with pagination & sorting)
/api/posts/{id}	GET	USER, ADMIN	Get a post by ID
/api/posts/{id}	PUT	ADMIN	Update a post
/api/posts/{id}	DELETE	ADMIN	Delete a post

💬 Comments

Endpoint	Method	Access	Description
/api/posts/{postId}/comments	POST	USER, ADMIN	Add a comment to a post
/api/posts/{postId}/comments	GET	USER, ADMIN	Get all comments for a post
/api/comments/{id}	DELETE	USER, ADMIN	Delete a comment

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🔒 JWT Security Flow

1. User registers or logs in → receives a JWT token
2. Client sends JWT in the Authorization header:

   Authorization: Bearer <your_token>

3. Every request is checked by JwtAuthenticationFilter
4. If the token is valid → request continues
5. If invalid → JwtAuthenticationEntryPoint returns Unauthorized (401)

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