Spring Boot Backend Development Course, Exploring Spring Boot 3

In this posting, we will conduct a course starting from the basic concepts of Spring Boot centered around the latest version, Spring Boot 3, including all the elements necessary for backend development. Spring Boot is a widely used framework in the Java development community that helps developers easily create Java web applications. This article will explain the features and advantages of Spring Boot, basic settings, building RESTful web services, database integration, security configurations, and more in detail.

1. What is Spring Boot?

Spring Boot is a lightweight framework based on the Spring Framework, developed to simplify the configuration and deployment of applications. Spring Boot helps developers quickly create standalone applications without complex XML configurations. Additionally, many default configurations are provided automatically, greatly improving development speed. Spring Boot shows its usefulness in both enterprise application development and personal projects.

2. Key Features of Spring Boot

  • Simplified Configuration: Automatically configures basic settings, so developers do not need to set them separately.
  • Standalone: Can run with an embedded web server (e.g., Tomcat, Jetty) without the need for a separate web server installation.
  • Increased Productivity: Allows easy initial configuration and project creation through tools like Spring Initializr.
  • Starter Dependencies: Allows easy addition of necessary dependencies by bundling various libraries.
  • Actuator: Provides monitoring and management capabilities for the application, making it easy to identify issues that occur during operation.

3. New Features of Spring Boot 3

Spring Boot 3 has introduced several new features and enhancements:

  • Support for JDK 17 or higher: Supports the latest Java LTS versions to improve performance and stability.
  • Integration with Spring Native: Improved native executable generation features make it easier for developers to use.
  • Improved Configuration Properties: Environment settings through @ConfigurationProperties have been made more intuitive.
  • Enhanced Modularity: Composed of more granular modules, allowing selective use of only the necessary parts as needed.

4. Installing and Configuring Spring Boot

4.1. Building the Development Environment

To develop with Spring Boot, the following elements are required:

  • Java Development Kit (JDK) – JDK 17 or higher is required.
  • Integrated Development Environment (IDE) – You can use IDEs like IntelliJ IDEA or Eclipse.
  • Maven or Gradle – You can choose either Maven or Gradle as dependency management tools.

4.2. Creating a Project with Spring Initializr

The easiest way to start a Spring Boot project is to use Spring Initializr. You can create a project through various integrated settings. Here’s how to set up a project:

  1. Access the website.
  2. Enter the project metadata (Group, Artifact, etc.).
  3. Select the dependencies (e.g., Spring Web, Spring Data JPA, etc.).
  4. Download the generated ZIP file and extract it.
  5. Open the project in your IDE.

5. Building RESTful Web Services

5.1. The Concept of REST

REST (Representational State Transfer) is a web-based architectural style that defines the way of communication between client and server. RESTful web services are based on the HTTP protocol and follow the principles:

  • Resource-Based – Resources are identified through URI.
  • Use of HTTP Methods – Resources are manipulated using methods such as GET, POST, PUT, DELETE.
  • Statelessness – The server does not maintain the state of the client.
  • Transfer of Representation – Data is sent in formats such as JSON and XML.

5.2. Implementing a RESTful API Using Spring Boot

Now, let’s implement a simple RESTful API using Spring Boot. Below is the process of creating a Todo application:

Step 1: Defining the Entity Class

package com.example.demo.model;

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

@Entity
public class Todo {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    private boolean completed;

    // Constructor, Getter, Setter omitted
}

Step 2: Creating the Repository Interface

package com.example.demo.repository;

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

public interface TodoRepository extends JpaRepository {
}

Step 3: Implementing the Service Class

package com.example.demo.service;

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

import java.util.List;

@Service
public class TodoService {
    @Autowired
    private TodoRepository todoRepository;

    public List getAllTodos() {
        return todoRepository.findAll();
    }

    public Todo createTodo(Todo todo) {
        return todoRepository.save(todo);
    }

    public void deleteTodo(Long id) {
        todoRepository.deleteById(id);
    }
}

Step 4: Creating the Controller

package com.example.demo.controller;

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

import java.util.List;

@RestController
@RequestMapping("/todos")
public class TodoController {
    @Autowired
    private TodoService todoService;

    @GetMapping
    public List getAllTodos() {
        return todoService.getAllTodos();
    }

    @PostMapping
    public Todo createTodo(@RequestBody Todo todo) {
        return todoService.createTodo(todo);
    }

    @DeleteMapping("/{id}")
    public void deleteTodo(@PathVariable Long id) {
        todoService.deleteTodo(id);
    }
}

6. Database Integration

Spring Boot can easily integrate with various databases. In this course, we will reinforce the Todo application using the H2 database.

6.1. Adding Dependencies

dependencies {
        implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
        implementation 'com.h2database:h2'
    }

6.2. Setting application.properties

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

By configuring as above, you can develop an application integrated with the H2 database. You can activate the H2 console to check the database directly.

7. Security Configuration

The security of web applications is a very important factor. Spring Boot can enhance security through Spring Security.

7.1. Adding Dependencies

dependencies {
        implementation 'org.springframework.boot:spring-boot-starter-security'
    }

7.2. Basic Security Configuration

With Spring Boot’s basic security configuration, you can require authentication for all requests. To do this, create a class that extends WebSecurityConfigurerAdapter.

package com.example.demo.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.authorizeRequests()
                .anyRequest().authenticated()
                .and()
                .httpBasic();
    }
}

8. Conclusion

Through this course, we have looked at the basic concepts and key features of Spring Boot 3, as well as the fundamentals of backend development that cover RESTful APIs, database integration, and security configurations. Spring Boot provides various functionalities needed by developers, which can enhance productivity and simplify the development process. We hope you will utilize Spring Boot in your future practical projects to develop various web applications.

9. Appendix

9.1. Useful Tools and Resources

9.2. Communities and Forums

There are many communities and forums where you can exchange questions or information related to Spring Boot. Some representative places are:

9.3. Recommended Books

Through this course, we hope you felt the charm of Spring Boot and built foundational knowledge to apply in real projects. Every developer finds it difficult to start. However, through consistent practice and learning, you can grow into a better developer.