[[servlet-events]]
== Authentication Events

For each authentication that succeeds or fails, a `AuthenticationSuccessEvent` or `AbstractAuthenticationFailureEvent` is fired, respectively.

To listen for these events, you must first publish an `AuthenticationEventPublisher`.
Spring Security's `DefaultAuthenticationEventPublisher` will probably do fine:

[source,java]
----
@Bean
public AuthenticationEventPublisher authenticationEventPublisher
        (ApplicationEventPublisher applicationEventPublisher) {
    return new DefaultAuthenticationEventPublisher(applicationEventPublisher);
}
----

Then, you can use Spring's `@EventListener` support:

[source,java]
----
@Component
public class AuthenticationEvents {
	@EventListener
    public void onSuccess(AuthenticationSuccessEvent success) {
		// ...
    }

    @EventListener
    public void onFailure(AbstractAuthenticationFailureEvent failures) {
		// ...
    }
}
----

While similar to `AuthenticationSuccessHandler` and `AuthenticationFailureHandler`, these are nice in that they can be used independently from the servlet API.

=== Adding Exception Mappings

`DefaultAuthenticationEventPublisher` by default will publish an `AbstractAuthenticationFailureEvent` for the following events:

|============
| Exception | Event
| `BadCredentialsException` | `AuthenticationFailureBadCredentialsEvent`
| `UsernameNotFoundException` | `AuthenticationFailureBadCredentialsEvent`
| `AccountExpiredException` | `AuthenticationFailureExpiredEvent`
| `ProviderNotFoundException` | `AuthenticationFailureProviderNotFoundEvent`
| `DisabledException` | `AuthenticationFailureDisabledEvent`
| `LockedException` | `AuthenticationFailureLockedEvent`
| `AuthenticationServiceException` | `AuthenticationFailureServiceExceptionEvent`
| `CredentialsExpiredException` | `AuthenticationFailureCredentialsExpiredEvent`
| `InvalidBearerTokenException` | `AuthenticationFailureBadCredentialsEvent`
|============

The publisher does an exact `Exception` match, which means that sub-classes of these exceptions won't also produce events.

To that end, you may want to supply additional mappings to the publisher via the `setAdditionalExceptionMappings` method:

[source,java]
----
@Bean
public AuthenticationEventPublisher authenticationEventPublisher
        (ApplicationEventPublisher applicationEventPublisher) {
    Map<Class<? extends AuthenticationException>,
        Class<? extends AbstractAuthenticationFailureEvent>> mapping =
            Collections.singletonMap(FooException.class, FooEvent.class);
    AuthenticationEventPublisher authenticationEventPublisher =
        new DefaultAuthenticationEventPublisher(applicationEventPublisher);
    authenticationEventPublisher.setAdditionalExceptionMappings(mapping);
    return authenticationEventPublisher;
}
----

=== Default Event

And, you can supply a catch-all event to fire in the case of any `AuthenticationException`:

[source,java]
----
@Bean
public AuthenticationEventPublisher authenticationEventPublisher
        (ApplicationEventPublisher applicationEventPublisher) {
    AuthenticationEventPublisher authenticationEventPublisher =
        new DefaultAuthenticationEventPublisher(applicationEventPublisher);
    authenticationEventPublisher.setDefaultAuthenticationFailureEvent
        (GenericAuthenticationFailureEvent.class);
    return authenticationEventPublisher;
}
----
