MVC Pattern in Spring MVC with a Blog Example

The Model-View-Controller (MVC) pattern is a design pattern that separates an application into three components: Model → Represents the data and business logic. View → Handles the UI/Presentation layer. Controller → Handles user requests, processes them, and sends data to the view. Spring MVC follows this pattern to build web applications in a structured and maintainable way. Let’s understand this with a blog application example where users can create, view, and manage blog posts. 1. Components of MVC in a Spring MVC Blog 1.1 Model (Data + Business Logic) The Model represents the blog post data and handles business logic. In Spring MVC, it is typically implemented using Java classes (POJOs), JPA/Hibernate entities, and Service Layer. Example: BlogPost Model @Entity public class BlogPost { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; private String title; private String content; private LocalDateTime createdAt; // Constructors, Getters, Setters } 1.2 View (User Interface) The View is responsible for rendering the response. In Spring MVC, the view is typically implemented using Thymeleaf, JSP, or other frontend technologies like React/Angular. Example: Thymeleaf View (blog.html) Blog Posts All Blog Posts Published on: 1.3 Controller (Handles Requests) The Controller manages incoming HTTP requests, processes data using the Model, and returns the appropriate View. In Spring MVC, controllers are implemented using @Controller or @RestController annotations. Example: BlogController @Controller @RequestMapping("/blog") public class BlogController { @Autowired private BlogService blogService; // Show all blog posts @GetMapping public String listPosts(Model model) { List posts = blogService.getAllPosts(); model.addAttribute("posts", posts); return "blog"; // Refers to blog.html } // Show the form to create a new post @GetMapping("/new") public String newPostForm(Model model) { model.addAttribute("blogPost", new BlogPost()); return "newPost"; // Refers to newPost.html } // Handle form submission for new post @PostMapping public String savePost(@ModelAttribute BlogPost blogPost) { blogService.savePost(blogPost); return "redirect:/blog"; // Redirect to list all posts } } 2. How MVC Works in Spring MVC (Request Flow) Example Scenario: A User Requests a Blog Post List User sends a request to /blog → GET /blog request is sent to BlogController. Controller Processes Request → listPosts(Model model) method fetches blog posts from BlogService. Model Passes Data to View → model.addAttribute("posts", posts); sends blog data to the view. View Displays Data → blog.html renders the list of blog posts with Thymeleaf. 3. Advantages of Using MVC in Spring MVC ✅ Separation of Concerns – Keeps business logic (Model), request handling (Controller), and UI (View) separate. ✅ Scalability – New features can be added easily. ✅ Maintainability – Easier to debug and update code. ✅ Reusable Components – Models and Views can be reused across multiple controllers. Final Thoughts Spring MVC provides a structured way to develop web applications using the MVC pattern. In a blog application, the Model (BlogPost) handles data, the View (Thymeleaf/JSP) renders UI, and the Controller (BlogController) processes requests. This architecture makes the application clean, maintainable, and scalable.

Mar 16, 2025 - 15:44

MVC Pattern in Spring MVC with a Blog Example

The Model-View-Controller (MVC) pattern is a design pattern that separates an application into three components:

Model → Represents the data and business logic.
View → Handles the UI/Presentation layer.
Controller → Handles user requests, processes them, and sends data to the view.

Spring MVC follows this pattern to build web applications in a structured and maintainable way. Let’s understand this with a blog application example where users can create, view, and manage blog posts.

1. Components of MVC in a Spring MVC Blog

1.1 Model (Data + Business Logic)

The Model represents the blog post data and handles business logic. In Spring MVC, it is typically implemented using Java classes (POJOs), JPA/Hibernate entities, and Service Layer.

Example: BlogPost Model

@Entity
public class BlogPost {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    private String content;
    private LocalDateTime createdAt;

    // Constructors, Getters, Setters
}

1.2 View (User Interface)

The View is responsible for rendering the response. In Spring MVC, the view is typically implemented using Thymeleaf, JSP, or other frontend technologies like React/Angular.

Example: Thymeleaf View (blog.html)


 xmlns:th="http://www.thymeleaf.org">

    </span>Blog Posts<span class="nt">


    All Blog Posts
    
         th:each="post : ${posts}">
             th:text="${post.title}">
             th:text="${post.content}">
            Published on:  th:text="${post.createdAt}">

1.3 Controller (Handles Requests)

The Controller manages incoming HTTP requests, processes data using the Model, and returns the appropriate View. In Spring MVC, controllers are implemented using @Controller or @RestController annotations.

Example: BlogController

@Controller
@RequestMapping("/blog")
public class BlogController {

    @Autowired
    private BlogService blogService;

    // Show all blog posts
    @GetMapping
    public String listPosts(Model model) {
        List<BlogPost> posts = blogService.getAllPosts();
        model.addAttribute("posts", posts);
        return "blog"; // Refers to blog.html
    }

    // Show the form to create a new post
    @GetMapping("/new")
    public String newPostForm(Model model) {
        model.addAttribute("blogPost", new BlogPost());
        return "newPost"; // Refers to newPost.html
    }

    // Handle form submission for new post
    @PostMapping
    public String savePost(@ModelAttribute BlogPost blogPost) {
        blogService.savePost(blogPost);
        return "redirect:/blog"; // Redirect to list all posts
    }
}

2. How MVC Works in Spring MVC (Request Flow)

Example Scenario: A User Requests a Blog Post List

User sends a request to /blog

→ GET /blog request is sent to BlogController.
Controller Processes Request

→ listPosts(Model model) method fetches blog posts from BlogService.
Model Passes Data to View

→ model.addAttribute("posts", posts); sends blog data to the view.
View Displays Data

→ blog.html renders the list of blog posts with Thymeleaf.

3. Advantages of Using MVC in Spring MVC

✅ Separation of Concerns – Keeps business logic (Model), request handling (Controller), and UI (View) separate.

✅ Scalability – New features can be added easily.

✅ Maintainability – Easier to debug and update code.

✅ Reusable Components – Models and Views can be reused across multiple controllers.

Final Thoughts

Spring MVC provides a structured way to develop web applications using the MVC pattern. In a blog application, the Model (BlogPost) handles data, the View (Thymeleaf/JSP) renders UI, and the Controller (BlogController) processes requests. This architecture makes the application clean, maintainable, and scalable.