Spring Boot Backend Development Course, Implementing Login and Logout with Spring Security, User Registration, Creating Views

In this course, we will learn how to develop backend applications using Spring Boot. Specifically, we will implement login/logout functionality and a registration system utilizing Spring Security, as well as cover the necessary content for creating views. Through this course, you will gain an understanding of the basic structure of web applications and their security aspects.

1. Introduction to Spring Boot

Spring Boot is a Java-based framework that provides tools for developing Spring applications quickly and simply. It simplifies the complex configurations often encountered in traditional Spring development, allowing developers to focus on business logic.

1.1 Advantages of Spring Boot

  • Auto-configuration: Spring Boot automatically configures the necessary settings when running the application.
  • Standalone: Spring Boot applications can run independently, including an embedded Tomcat server.
  • Convenient dependency management: Library dependencies can be easily managed via Maven or Gradle.

2. Setting Up Security with Spring Security

Spring Security provides robust authentication and authorization features for securing Spring-based applications. In this section, we will learn how to configure Spring Security and implement login and logout functionality.

2.1 Adding Dependencies

To use Spring Security, add the following dependencies to the build.gradle file:

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

2.2 Creating the Spring Security Configuration Class

We will create a SecurityConfig class for Spring Security configuration. The code below includes basic login and logout settings:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
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;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.inMemoryAuthentication()
            .withUser("user").password(passwordEncoder().encode("password")).roles("USER")
            .and()
            .withUser("admin").password(passwordEncoder().encode("admin")).roles("ADMIN");
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .authorizeRequests()
                .antMatchers("/", "/register").permitAll()
                .anyRequest().authenticated()
                .and()
            .formLogin()
                .loginPage("/login")
                .permitAll()
                .and()
            .logout()
                .permitAll();
    }

    @Bean
    public PasswordEncoder passwordEncoder() {
        return new BCryptPasswordEncoder();
    }
}

3. Implementing Registration Functionality

To implement the registration functionality, we will create an entity to store user information and a repository for database integration. After that, we will create a controller to handle the registration process.

3.1 Creating the User Entity

We will write a User class to store user information:

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 username;
    private String password;
    private String email;

    // getters and setters
}

3.2 Creating the UserRepository

We will create a repository to manage User information using JPA:

import org.springframework.data.jpa.repository.JpaRepository;

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

3.3 Creating Registration Form and Controller

We will create an HTML form for registration and a controller to handle it. We will create a RegisterController to process registration requests:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/register")
public class RegisterController {

    @Autowired
    private UserRepository userRepository;

    @GetMapping
    public String showRegisterForm(Model model) {
        model.addAttribute("user", new User());
        return "register";
    }

    @PostMapping
    public String registerUser(User user) {
        user.setPassword(new BCryptPasswordEncoder().encode(user.getPassword()));
        userRepository.save(user);
        return "redirect:/login";
    }
}

3.4 Creating Registration HTML Form

We will create a form for registration:





    Registration


    
Registration

4. Implementing Login/Logout Functionality

We will implement the login and logout functionality to allow users to securely access the system.

4.1 Creating Login HTML Form

We will create the login form:





    Login


    
Login

4.2 Handling Logout

The logout functionality is provided by Spring Security by default, specifying a logout URL through which logout is processed. It uses the default /logout path.

5. Creating Views

Now that we have implemented the registration and login functionality, we will create the views that will be displayed to the users. When using Spring Boot, we mainly use a template engine called Thymeleaf.

5.1 Setting Up Thymeleaf

To use Thymeleaf, add the following dependency to the build.gradle file:

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

5.2 Creating a Basic Home Page

We will create a controller and view to display the home page. Below is the HTML code representing the home page:





    Home


    
Home Page

    

        Hello, User!
        Logout
    

    

        Login
        

        Register

6. Conclusion

In this way, we have built a web application with simple registration and login/logout functionality using Spring Boot. Through this project, you will understand the basic usage of Spring Boot and implementing security features using Spring Security.

6.1 Next Steps

You can now consider adding more complex features or developing a RESTful API to communicate with the frontend. It is also good to think about integration with mobile applications or other clients. If necessary, integrating external authentication services like OAuth2 is also a good direction.

6.2 Additional Resources

If you want more information, please refer to the official Spring Boot documentation and Spring Security documentation: