WebSecurityConfig

@Configuration
@EnableWebMvcSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {

    @Bean
    public ServiceProperties serviceProperties() {
        ServiceProperties serviceProperties = new ServiceProperties();
        serviceProperties.setService("https://localhost:8443/cas-sample/j_spring_cas_security_check");
        serviceProperties.setSendRenew(false);
        return serviceProperties;
    }

    @Bean
    public CasAuthenticationProvider casAuthenticationProvider() {
        CasAuthenticationProvider casAuthenticationProvider = new CasAuthenticationProvider();
        casAuthenticationProvider.setAuthenticationUserDetailsService(authenticationUserDetailsService());
        casAuthenticationProvider.setServiceProperties(serviceProperties());
        casAuthenticationProvider.setTicketValidator(cas20ServiceTicketValidator());
        casAuthenticationProvider.setKey("an_id_for_this_auth_provider_only");
        return casAuthenticationProvider;
    }

    @Bean
    public AuthenticationUserDetailsService authenticationUserDetailsService() {
        return new TestCasAuthenticationUserDetailsService();
    }

    @Bean
    public Cas20ServiceTicketValidator cas20ServiceTicketValidator() {
        return new Cas20ServiceTicketValidator("https://localhost:9443/cas)";
    }

    @Bean
    public CasAuthenticationFilter casAuthenticationFilter() throws Exception {
        CasAuthenticationFilter casAuthenticationFilter = new CasAuthenticationFilter();
        casAuthenticationFilter.setAuthenticationManager(authenticationManager());
        return casAuthenticationFilter;
    }

    @Bean
    public CasAuthenticationEntryPoint casAuthenticationEntryPoint() {
        CasAuthenticationEntryPoint casAuthenticationEntryPoint = new CasAuthenticationEntryPoint();
        casAuthenticationEntryPoint.setLoginUrl("https://localhost:9443/cas/login");
        casAuthenticationEntryPoint.setServiceProperties(serviceProperties());
        return casAuthenticationEntryPoint;
    }

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
            .addFilter(casAuthenticationFilter());
        http
            .exceptionHandling()
                .authenticationEntryPoint(casAuthenticationEntryPoint());
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth
            .authenticationProvider(casAuthenticationProvider());
    }
}