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)
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<title>Blog Posts</title>
</head>
<body>
<h1>All Blog Posts</h1>
<ul>
<li th:each="post : ${posts}">
<h2 th:text="${post.title}"></h2>
<p th:text="${post.content}"></p>
<p><i>Published on: <span th:text="${post.createdAt}"></span></i></p>
</li>
</ul>
</body>
</html>
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 /blogrequest is sent toBlogController.Controller Processes Request
→listPosts(Model model)method fetches blog posts fromBlogService.Model Passes Data to View
→model.addAttribute("posts", posts);sends blog data to the view.View Displays Data
→blog.htmlrenders 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. 🚀
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