Basics of Spring Security in Spring Boot

Spring Security is a powerful framework that provides authentication, authorization, and access control for web applications. In this blog post, we will explore how to use Spring Security to secure a web application with code examples.

Step 1: Setting up the project

The first step is to set up a Spring Boot project with the necessary dependencies. We will use Spring Boot Starter Web and Spring Security dependencies. To set up the project, create a new Spring Boot project in your IDE of choice and add the following dependencies to your pom.xml file:

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-security</artifactId>
</dependency>

Step 2: Creating a UserDetailsService

The UserDetailsService interface is used to retrieve user details from a database or any other data source. We will create an implementation of this interface to retrieve user details from a database. Here’s an example:

@Service
public class UserDetailsServiceImpl implements UserDetailsService {
   @Autowired
   private UserRepository userRepository;
   @Override
   public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
       User user = userRepository.findByUsername(username);
       if(user == null) {
           throw new UsernameNotFoundException("User not found");
       }
       return new org.springframework.security.core.userdetails.User(user.getUsername(),
               user.getPassword(),
               Collections.singleton(new SimpleGrantedAuthority(user.getRole().name())));
   }
}

Step 3: Configuring Security

To configure Spring Security, we need to create a SecurityConfig class that extends WebSecurityConfigurerAdapter. Here’s an example:

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {
   @Autowired…