Spring Boot Login/Logout (Spring Security + MySql + Thymeleaf)

Mar 31, 2024

Updated for: Spring Boot 3

This article is going to discuss how to implement "login/logout" and "authentication/authorization" in a "Spring Boot 3" application.

To demonstrate the functionality, a new "Spring Boot" application is created with the help of spring initializr.

In order to save/get user details (name, email or username, roles) the application is using the "MySql" database. The application also uses thymeleaf as a server-side template engine.

The idea is to create a custom "registration" and "login" flow based on "thymeleaf (html)" forms.

Prerequisite

This application requires an existing database in MySql; this can be achieved with the help of the below-mentioned query:

CREATE SCHEMA `spring-security-form-login` ;

Dependencies

pom.xml

The "spring-boot-starter-security" combines Spring Security dependencies, and the "spring-boot-starter-web" enables "Tomcat" as a default embedded server.

Like wise, "spring-boot-starter-data-jpa" provides the "data-jpa" dependency to efficiently connect Spring applications with relational databases.

In total, the application requires the below-mentioned dependencies:

Configuration

src/main/java/com/cb/conf/SpringSecurity.java

The "SecurityFilterChain" defines a filter chain that is capable of being matched against an HttpServletRequest.

As mentioned in the configuration below, the urls matching with "/user/**" are accessible by users having either the "USER" or "ADMIN" role, whereas the urls matching with "/admin/**" are only accessible by users having the "ADMIN" role.

On the other hand, urls beginning with "/registration/**" and "/login/**" are accessible by both authenticated and non-authenticated users, or accessible by all.

Model

src/main/java/com/cb/model/User.java

The "User" and "Role" are plain old models representing a Spring Security user and associated role in the application and database.

src/main/java/com/cb/model/Role.java

The "Role" class has a list of users, which means a user can have multiple roles, and a role can be associated with a number of users.

DTO

src/main/java/com/cb/dto/UserDto.java

The "UserDto" class is a helper class to be used in "Html form to Controller communication" when a new user is registered in the system.

Repository

src/main/java/com/cb/repository/UserRepository.java

The "UserRepository" and "RoleRepository" are using Spring Data JPA to significantly improve the implementation of data access layers by reducing the effort to the amount that's actually needed.

src/main/java/com/cb/repository/RoleRepository.java

The "findByName" method gets the "Role" object for the associated "role" name.

Service

src/main/java/com/cb/service/UserService.java

"UserService.java" and "UserServiceImpl.java" represent an intermediate service layer between data/repository and controller.

src/main/java/com/cb/service/UserServiceImpl.java

The "saveUser()" method converts "UserDto" to "User" and saves it in the database (MySql).

src/main/java/com/cb/service/CustomUserDetailsService.java

This "CustomUserDetailsService" is a custom implementation of "UserDetailsService" and is used by Spring to get user details from the database during a login flow.

Controller

src/main/java/com/cb/controller/LoginController.java

This "LoginController" hosts "request-mappings" for "Login" and "Registration" related UI (HTML + Thymeleaf).

src/main/java/com/cb/controller/UserController.java

This "UserController" hosts a single "request-mappings" for "user-details" related UI (HTML + Thymeleaf).

Constants

src/main/java/com/cb/util/TbConstants.java

The "TbConstants.java" maintains constants used throughout the application; this helps make the application code more maintainable.

Application

src/main/java/com/cb/Application.java

This is the simple "spring boot" "main" class; all the application execution starts from here.

The only interesting thing to note is the exclusion of "SecurityAutoConfiguration.class" and "Management- WebSecurityAutoConfiguration.class". This is required to disable security auto-configuration so that we can have our own settings, like a custom login form.

HTML

src/main/resources/templates/registration.html

The "registration.html" is a simple ".html" file with "thymeleaf" template capabilities. This page contains a server-side validation-enabled "registration" form.

src/main/resources/templates/login.html

By default spring security accepts login request at "/login" and credentials in the form of "username" and "password".

src/main/resources/templates/user.html

The "thymeleaf" template engine enables us to use "sec:authentication" tags to display security-related information in HTML.

src/main/resources/application.yml

This "application.yml" file contains "db credentials,"  "hibernate" settings, and "thread-pool" configurations.

Testing

1) Registration

Let's run the application and start testing the functionality by registering a new user at : http://localhost:8080/registration.

2) Login

Now that a new user has been successfully registered, we can use the credentials to login at: http://localhost:8080/login.

3) Details

The user is now "logged-in" to the system with "role_user" and hence URLs accessible by "role_user" can be viewed: http://localhost:8080/user/.

3) Logout

In order to log-out from the system, we can send a get call to "http://localhost:8080/logout" i.e. click on: http://localhost:8080/logout.

Source code: GitHub