Spring Boot Backend Development Course, Blog Production Example, Repository Creation

1. Introduction

Spring Boot is a Java-based framework that helps to develop applications quickly and easily. This course explains the core concepts and technologies needed to build a blog web application using Spring Boot. You will cover topics such as database integration, REST API design, and communication with the frontend.

1.1. Course Objectives

  • Understanding the basic concepts of Spring Boot
  • Designing and implementing RESTful APIs
  • Learning how to integrate with databases using JPA
  • User authentication and authorization management using Spring Security
  • Implementing functionalities through communication with the frontend

2. Environment Setup

To develop a Spring Boot application, the following development environment is required.

2.1. Prerequisites

  • Java 11 or higher
  • Spring Boot 2.5 or higher
  • Maven or Gradle (dependency management tools)
  • IDE (IntelliJ IDEA, Eclipse, etc.)

2.2. Setting Up the Development Environment

Follow the steps below to set up the development environment. Install the JAVA JDK, then install the IDE and add the required plugins and libraries.

3. Creating a Spring Boot Project

There are many ways to create a Spring Boot project, but the simplest method is to use Spring Initializr.

3.1. Creating a Project Using Spring Initializr

  1. Open the Spring Initializr page in your web browser.
  2. Set up the project metadata.

  3. Project

    Select Maven Project or Gradle Project

  4. Language

    Select Java

  5. Spring Boot

    Select the latest stable version

  6. Project Metadata

    Set the Group and Artifact.

  7. Dependencies

    Add Web, JPA, H2 Database, Security.

  8. Click the Generate button to download the project.

4. Understanding the Project Structure

The structure of a Spring Boot project is the same as a typical Maven project, but there are some differences according to Spring Boot’s conventions. Below is the basic project structure.

        └── demo
            ├── DemoApplication.java
            ├── controller
            ├── model
            ├── repository
            └── service

4.1. Description of Main Packages

  • controller: Contains controller classes that handle web requests.
  • service: Contains service classes that implement business logic.
  • repository: Contains repository classes responsible for interacting with the database.
  • model: Contains classes that define database entities.

5. Designing the Blog Domain Model

Define the domain model for the blog application. This model includes Post and User entities.

5.1. Post Entity


    @Entity
    public class Post {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;
        private String title;
        private String content;
        
        @ManyToOne
        private User author;

        // Getters and Setters
    }

5.2. User Entity


    @Entity
    public class User {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;
        private String username;
        private String password;

        @OneToMany(mappedBy = "author")
        private List posts;

        // Getters and Setters
    }

6. Creating Repository Interfaces

Create repository interfaces to access the database using JPA. With Spring Data JPA, CRUD operations can be performed easily.

6.1. PostRepository


    public interface PostRepository extends JpaRepository {
    }

6.2. UserRepository


    public interface UserRepository extends JpaRepository {
        Optional findByUsername(String username);
    }

7. Implementing Services

Implement the service layer to handle business logic. The service calls the repositories to perform DB operations and apply necessary business rules.

7.1. PostService


    @Service
    public class PostService {
        @Autowired
        private PostRepository postRepository;

        public List getAllPosts() {
            return postRepository.findAll();
        }

        public Post createPost(Post post) {
            return postRepository.save(post);
        }
    }

7.2. UserService


    @Service
    public class UserService {
        @Autowired
        private UserRepository userRepository;

        public User findUserByUsername(String username) {
            return userRepository.findByUsername(username).orElse(null);
        }

        public User createUser(User user) {
            return userRepository.save(user);
        }
    }

8. Implementing Controllers

Implement controllers to handle user requests. Design RESTful web services to manage communication between clients and servers.

8.1. PostController


    @RestController
    @RequestMapping("/api/posts")
    public class PostController {
        @Autowired
        private PostService postService;

        @GetMapping
        public List getAllPosts() {
            return postService.getAllPosts();
        }

        @PostMapping
        public Post createPost(@RequestBody Post post) {
            return postService.createPost(post);
        }
    }

8.2. UserController


    @RestController
    @RequestMapping("/api/users")
    public class UserController {
        @Autowired
        private UserService userService;

        @PostMapping
        public User createUser(@RequestBody User user) {
            return userService.createUser(user);
        }

        @GetMapping("/{username}")
        public User getUserByUsername(@PathVariable String username) {
            return userService.findUserByUsername(username);
        }
    }

9. Configuring Spring Security

Set up Spring Security for user authentication and authorization management. Configure the base security settings to protect URLs and user authentication mechanisms.


    @Configuration
    @EnableWebSecurity
    public class SecurityConfig extends WebSecurityConfigurerAdapter {
        @Override
        protected void configure(HttpSecurity http) throws Exception {
            http
                .authorizeRequests()
                .antMatchers("/api/users").permitAll()
                .anyRequest().authenticated()
                .and()
                .formLogin();
        }
    }

10. Running and Testing the Application

Now you’re ready to run the application and test the API using tools like Postman. Make sure each endpoint works correctly.

10.1. Running the Application

For IntelliJ IDEA, you can run the application by clicking the Run icon in the main class or execute the following command in the command line.

./mvnw spring-boot:run

10.2. Testing with Postman

You can test the REST API using Postman. Here are some basic testing examples.

  • GET /api/posts: Retrieve all posts
  • POST /api/posts: Create a new post
  • GET /api/users/{username}: Retrieve information for a specific user
  • POST /api/users: Create a new user

11. Conclusion

Through this course, you learned how to build a simple blog application using Spring Boot. This example allowed you to cover various topics such as REST API design, database integration, and implementation of services and controllers. Going forward, try to challenge yourself to develop more complex applications based on this foundation.

12. References