Spring Boot Backend Development Course, Understanding the Project with Illustrations

Hello! In this course, we will cover the basics to advanced topics of backend development using Spring Boot. This course is designed to be visually easy to understand with illustrations, making it accessible for beginners. This step-by-step project covers all the elements needed to develop a real web application.

1. What is Spring Boot?

Spring Boot is a modern lightweight framework based on the Spring Framework. It minimizes the time developers spend on setup and configuration tasks, fundamentally simplifying the bootstrap process of Spring applications.

Spring Boot Architecture

Figure 1: Spring Boot Architecture

The main advantages of Spring Boot are as follows:

  • Fast development: Provides an embedded Tomcat server and automatic configuration features.
  • Easy deployment: Can be easily deployed on various platforms.
  • Productive development: Powerful features can be accessed with simple setup.

2. Setting Up the Development Environment

To develop a Spring Boot application, you need to install JDK, Maven, and an IDE. Here’s how to set up each tool.

2.1 Installing JDK

To use Spring Boot, you need to install the Java Development Kit (JDK). Download and install the latest version of the JDK. After installation, set the JAVA_HOME environment variable.

2.2 Installing Maven

Maven is a tool for dependency management. After installing Maven, add the Maven bin path to the PATH environment variable.

2.3 Installing an IDE

You can conveniently manage Spring Boot projects using IDEs like IntelliJ IDEA or Eclipse. IntelliJ IDEA, in particular, is highly recommended due to its excellent support for integration with Spring Boot.

3. Creating Your First Spring Boot Project

Now let’s create a Spring Boot project. You can use Spring Initializr to generate the project. Follow the steps below:

  1. Access the Spring Initializr website.
  2. Enter the project metadata.
  3. Add dependencies. (Spring Web, Spring Data JPA, H2 Database, etc.)
  4. Download the project and open it in your IDE.

3.1 Understanding the Project Structure

The generated project has the following structure:

my-spring-boot-project/
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/
│   │   │       └── example/
│   │   │           └── demo/
│   │   │               ├── DemoApplication.java
│   │   │               └── controller/
│   │   │               └── service/
│   │   │               └── repository/
│   │   └── resources/
│   │       ├── application.properties
│   └── test/
│       └── java/
└── pom.xml

In this structure, DemoApplication.java serves as the entry point of the application.

4. Developing a RESTful API

Now let’s create a basic RESTful API. Spring Boot supports building RESTful services very easily.

4.1 Creating the Model Class

First, let’s create a data model class. For example, we will create a User class to store user information.

package com.example.demo.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

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

    // getters and setters
}

4.2 Creating the Repository Interface

To query or modify data, let’s create a repository interface using JPA.

package com.example.demo.repository;

import com.example.demo.model.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository {
}

4.3 Creating the Service Class

Let’s create a service class to handle business logic.

package com.example.demo.service;

import com.example.demo.model.User;
import com.example.demo.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

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

    public List getAllUsers() {
        return userRepository.findAll();
    }

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

    // Other methods
}

4.4 Creating the Controller Class

Now let’s create a controller class to handle HTTP requests.

package com.example.demo.controller;

import com.example.demo.model.User;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

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

    @GetMapping
    public List getAllUsers() {
        return userService.getAllUsers();
    }

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

5. Database Configuration

Now let’s set up the H2 database. Modify the application.properties file to add the database configuration.

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=password
spring.h2.console.enabled=true
spring.jpa.hibernate.ddl-auto=update

6. Testing

Now everything is ready. When you run the Spring Boot application, you can create and query user data through the RESTful API using the embedded H2 database. Tools like Postman can be used to perform API testing.

Postman Usage Example

Figure 2: API Testing in Postman

7. Conclusion

In this course, you learned how to create a simple backend application using Spring Boot. Spring Boot helps you progress projects quickly without complex configurations and is very suitable for developing RESTful APIs. I hope this course has laid the foundation for you to delve deeper into backend development with Spring Boot.

8. Additional Resources

If you want to learn more, check out the resources below: