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

@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {


    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
                .authorizeRequests()
                    .antMatchers("/", "/login_error_handler").permitAll()
                    .anyRequest().authenticated()
                .and()
                    // use the login page
                    .formLogin()
                    // use customized login page
                    // can only use this name
                    .loginPage("/login")
                    // everyone can visit the /login
                    .permitAll()
                    // if login successfully
                    // for unsecured endpoint
                    // will be directed here
                    // the endpoint is mapped in WebMVCConfig
                    .defaultSuccessUrl("/login_success")
                    // if login failed
                    // replace default /login?error
                    // the endpoint is mapped in WebMVCConfig
                    .failureUrl("/login_error")
                    // if login successfully
                    // execute some extra code
                    // the endpoint is mapped in @Controller
                    // will override .defaultSuccessUrl
                    .successForwardUrl("/login_success_forward")
                    // if login failed
                    // execute some extra code
                    // the endpoint is mapped in @Controller
                    // will override .failureUrl
                    .failureForwardUrl("/login_error_forward")

                    .successHandler(new AuthenticationSuccessHandler() {

                        @Override
                        public void onAuthenticationSuccess(HttpServletRequest request,
                                                            HttpServletResponse response,
                                                            Authentication authentication) throws IOException, ServletException {

                            System.out.println("[shark] Logged user: " + authentication.getName());

                            response.sendRedirect("/login_success_handler");
                        }
                    })

                    .failureHandler(new AuthenticationFailureHandler() {

                        @Override
                        public void onAuthenticationFailure(HttpServletRequest request,
                                                            HttpServletResponse response,
                                                            AuthenticationException exception) throws IOException, ServletException {
                            System.out.println("[shark] Login failed");
                            System.out.println(exception);

                            // needs to open visit
                            response.sendRedirect("/login_error_handler");
                        }
                    });



    }







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

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



}

@Configuration
public class WebMVCConfig implements WebMvcConfigurer {
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {

        registry.addViewController("/").setViewName("index");
        registry.addViewController("/home").setViewName("home");

        registry.addViewController("/login").setViewName("login");
        registry.addViewController("/login_success").setViewName("login_success");
        registry.addViewController("/login_error").setViewName("login_error");


        registry.addViewController("/login_success_handler").setViewName("login_success_handler");
        registry.addViewController("/login_error_handler").setViewName("login_error_handler");


    }


}

<!DOCTYPE html>
<html xmlns:th="http:/www.thymeleaf.org">
<head>
    <meta charset="ISO-8859-1">
    <title>Login - Company ABC</title>
</head>
<body>
<div>
    <form th:action="@{/login}" method="post" style="max-width: 400px; margin: 0 auto;">
        <p>
            Username: <input type="text" name="username" required />
        </p>
        <p>
            Password: <input type="password" name="password" required />
        </p>
        <p>
            <input type="submit" value="Login" />
        </p>
    </form>
</div>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Login Successfully
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Oops,you log in wrongly.
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Login Successfully Forward
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Login Error Forward
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Login Successfully Handler
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Login Error Handler
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Home (protected)
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
Index (not protected)
</body>
</html>

<!DOCTYPE html>
<html>
<head>
    <title>Error occurred</title>
</head>
<body>
<h1>Error occurred</h1>

<p>
    An error has occurred. Please contact the administrator; - template generic
</p>

</body>
</html>