Чё-то делаю...

spring_online_calculator/src/main/java/premium_store/configuration/SecurityConfiguration.java

@@ -10,15 +10,17 @@ import org.springframework.security.config.annotation.authentication.builders.Au
 import org.springframework.security.config.annotation.method.configuration.EnableMethodSecurity;
 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.config.annotation.web.configuration.WebSecurityCustomizer;
 import org.springframework.security.web.SecurityFilterChain;
+import premium_store.service.UserService;
 
 @Configuration
 @EnableWebSecurity
 @EnableMethodSecurity(
         securedEnabled = true
 )
-public class SecurityConfiguration {
+public class SecurityConfiguration extends WebSecurityConfigurerAdapter {
     private final Logger log = LoggerFactory.getLogger(SecurityConfiguration.class);
     private static final String LOGIN_URL = "/login";
     private final UserService userService;
@@ -32,7 +34,7 @@ public class SecurityConfiguration {
         final String admin = "admin";
         if (userService.findByLogin(admin) == null) {
             log.info("Admin user successfully created");
-            userService.addUser(admin, "adminemail@gmail.com", admin, admin, UserRole.ADMIN);
+            userService.createUser(admin, "adminemail@gmail.com", admin, admin, UserRole.ADMIN);
         }
     }
 
@@ -70,4 +72,9 @@ public class SecurityConfiguration {
                 .requestMatchers("/templates/**")
                 .requestMatchers("/webjars/**");
     }
+
+    @Override
+    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
+        auth.userDetailsService(userService);
+    }
 }

spring_online_calculator/src/main/java/premium_store/service/UserService.java

@@ -0,0 +1,62 @@
+package premium_store.service;
+
+import org.springframework.security.core.userdetails.UserDetails;
+import org.springframework.security.core.userdetails.UserDetailsService;
+import org.springframework.security.core.userdetails.UsernameNotFoundException;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.stereotype.Service;
+import premium_store.model.GameClient;
+import premium_store.repository.GameClientRepository;
+import premium_store.util.validation.ValidatorUtil;
+
+import javax.validation.ValidationException;
+import java.util.Collections;
+import java.util.Objects;
+
+@Service
+public class UserService implements UserDetailsService {
+    private final GameClientRepository userRepository;
+    private final PasswordEncoder passwordEncoder;
+    private final ValidatorUtil validatorUtil;
+
+    public UserService(GameClientRepository userRepository,
+                       PasswordEncoder passwordEncoder,
+                       ValidatorUtil validatorUtil) {
+        this.userRepository = userRepository;
+        this.passwordEncoder = passwordEncoder;
+        this.validatorUtil = validatorUtil;
+    }
+
+    public GameClient findByLogin(String login) {
+        return userRepository.findOneByLoginIgnoreCase(login);
+    }
+
+    public GameClient createUser(String login, String password, String passwordConfirm) {
+        if (findByLogin(login) != null) {
+            throw new ValidationException(String.format("User '%s' already exists", login));
+        }
+
+        final GameClient user = new GameClient(login, passwordEncoder.encode(password), 0);
+
+        validatorUtil.validate(user);
+
+        if (!Objects.equals(password, passwordConfirm)) {
+            throw new ValidationException("Passwords not equals");
+        }
+
+        return userRepository.save(user);
+    }
+
+    @Override
+    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
+        final GameClient userEntity = findByLogin(username);
+
+        if (userEntity == null) {
+            throw new UsernameNotFoundException(username);
+        }
+
+        return new org.springframework.security.core.userdetails.User(
+                userEntity.getNickName(), userEntity.getEmail(), Collections.emptyList());
+    }
+
+}

spring_online_calculator/src/main/resources/templates/signup.html

@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<html lang="en"
+      xmlns:th="http://www.thymeleaf.org"
+      xmlns:layout="http://www.ultraq.net.nz/thymeleaf/layout"
+      layout:decorate="~{default}">
+<head>
+    <script type="text/javascript" src="/webjars/jquery/3.6.0/jquery.min.js"></script>
+</head>
+<body>
+<div class="container container-padding" layout:fragment="content">
+    <div th:if="${errors}" th:text="${errors}" class="margin-bottom alert alert-danger"></div>
+    <form action="#" th:action="@{/signup}" th:object="${userDto}" method="post">
+        <div class="mb-3">
+            <input type="text" class="form-control" th:field="${userDto.login}“
+                placeholder="Логин" required="true" autofocus="true" maxlength="64"/>
+        </div>
+        <div class="mb-3">
+            <input type="password" class="form-control" th:field="${userDto.password}“
+                placeholder="Пароль" required="true" minlength="6" maxlength="64"/>
+        </div>
+        <div class="mb-3">
+            <input type="password" class="form-control" th:field="${userDto.passwordConfirm}“
+                placeholder="Пароль (подтверждение)" required="true" minlength="6" maxlength="64"/>
+        </div>
+        <div class="mb-3">
+            <button type="submit" class="btn btn-success button-fixed">Создать</button>
+            <a class="btn btn-primary button-fixed" href="/login">Назад</a>
+        </div>
+    </form>
+</div>
+</body>
+</html>