This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Session 3.1.7!

Redis Configurations

Now that you have your application configured, you might want to start customizing things:

Serializing the Session using JSON

By default, Spring Session uses Java Serialization to serialize the session attributes. Sometimes it might be problematic, especially when you have multiple applications that use the same Redis instance but have different versions of the same class. You can provide a RedisSerializer bean to customize how the session is serialized into Redis. Spring Data Redis provides the GenericJackson2JsonRedisSerializer that serializes and deserializes objects using Jackson’s ObjectMapper.

Configuring the RedisSerializer
@Configuration
public class SessionConfig implements BeanClassLoaderAware {

	private ClassLoader loader;

	@Bean
	public RedisSerializer<Object> springSessionDefaultRedisSerializer() {
		return new GenericJackson2JsonRedisSerializer(objectMapper());
	}

	/**
	 * Customized {@link ObjectMapper} to add mix-in for class that doesn't have default
	 * constructors
	 * @return the {@link ObjectMapper} to use
	 */
	private ObjectMapper objectMapper() {
		ObjectMapper mapper = new ObjectMapper();
		mapper.registerModules(SecurityJackson2Modules.getModules(this.loader));
		return mapper;
	}

	/*
	 * @see
	 * org.springframework.beans.factory.BeanClassLoaderAware#setBeanClassLoader(java.lang
	 * .ClassLoader)
	 */
	@Override
	public void setBeanClassLoader(ClassLoader classLoader) {
		this.loader = classLoader;
	}

}

The above code snippet is using Spring Security, therefore we are creating a custom ObjectMapper that uses Spring Security’s Jackson modules. If you do not need Spring Security Jackson modules, you can inject your application’s ObjectMapper bean and use it like so:

@Bean
public RedisSerializer<Object> springSessionDefaultRedisSerializer(ObjectMapper objectMapper) {
    return new GenericJackson2JsonRedisSerializer(objectMapper);
}

Specifying a Different Namespace

It is not uncommon to have multiple applications that use the same Redis instance. For that reason, Spring Session uses a namespace (defaults to spring:session) to keep the session data separated if needed.

Using Spring Boot Properties

You can specify it by setting the spring.session.redis.namespace property.

  • application.properties

  • application.yml

spring.session.redis.namespace=spring:session:myapplication
spring:
  session:
    redis:
      namespace: "spring:session:myapplication"

Using the Annotation’s Attributes

You can specify the namespace by setting the redisNamespace property in the @EnableRedisHttpSession, @EnableRedisIndexedHttpSession, or @EnableRedisWebSession annotations:

  • @EnableRedisHttpSession

  • @EnableRedisIndexedHttpSession

  • @EnableRedisWebSession

@Configuration
@EnableRedisHttpSession(redisNamespace = "spring:session:myapplication")
public class SessionConfig {
    // ...
}
@Configuration
@EnableRedisIndexedHttpSession(redisNamespace = "spring:session:myapplication")
public class SessionConfig {
    // ...
}
@Configuration
@EnableRedisWebSession(redisNamespace = "spring:session:myapplication")
public class SessionConfig {
    // ...
}

Choosing Between RedisSessionRepository and RedisIndexedSessionRepository

When working with Spring Session Redis, you will likely have to choose between the RedisSessionRepository and the RedisIndexedSessionRepository. Both are implementations of the SessionRepository interface that store session data in Redis. However, they differ in how they handle session indexing and querying.

  • RedisSessionRepository: RedisSessionRepository is a basic implementation that stores session data in Redis without any additional indexing. It uses a simple key-value structure to store session attributes. Each session is assigned a unique session ID, and the session data is stored under a Redis key associated with that ID. When a session needs to be retrieved, the repository queries Redis using the session ID to fetch the associated session data. Since there is no indexing, querying sessions based on attributes or criteria other than the session ID can be inefficient.

  • RedisIndexedSessionRepository: RedisIndexedSessionRepository is an extended implementation that provides indexing capabilities for sessions stored in Redis. It introduces additional data structures in Redis to efficiently query sessions based on attributes or criteria. In addition to the key-value structure used by RedisSessionRepository, it maintains additional indexes to enable fast lookups. For example, it may create indexes based on session attributes like user ID or last access time. These indexes allow for efficient querying of sessions based on specific criteria, enhancing performance and enabling advanced session management features. In addition to that, RedisIndexedSessionRepository also supports session expiration and deletion.

Configuring the RedisSessionRepository

Using Spring Boot Properties

If you are using Spring Boot, the RedisSessionRepository is the default implementation. However, if you want to be explicit about it, you can set the following property in your application:

  • application.properties

  • application.yml

spring.session.redis.repository-type=default
spring:
  session:
    redis:
      repository-type: default

Using Annotations

You can configure the RedisSessionRepository by using the @EnableRedisHttpSession annotation:

@Configuration
@EnableRedisHttpSession
public class SessionConfig {
    // ...
}

Configuring the RedisIndexedSessionRepository

Using Spring Boot Properties

You can configure the RedisIndexedSessionRepository by setting the following properties in your application:

  • application.properties

  • application.yml

spring.session.redis.repository-type=indexed
spring:
  session:
    redis:
      repository-type: indexed

Using Annotations

You can configure the RedisIndexedSessionRepository by using the @EnableRedisIndexedHttpSession annotation:

@Configuration
@EnableRedisIndexedHttpSession
public class SessionConfig {
    // ...
}

Listening to Session Events

Often times it is valuable to react to session events, for example, you might want to do some kind of processing depending on the session lifecycle. In order to be able to do that, you must be using the indexed repository. If you do not know the difference between the indexed and the default repository, you can go to this section.

With the indexed repository configured, you can now start to listen to SessionCreatedEvent, SessionDeletedEvent, SessionDestroyedEvent and SessionExpiredEvent events. There are a few ways to listen to application events in Spring, we are going to use the @EventListener annotation.

@Component
public class SessionEventListener {

    @EventListener
    public void processSessionCreatedEvent(SessionCreatedEvent event) {
        // do the necessary work
    }

    @EventListener
    public void processSessionDeletedEvent(SessionDeletedEvent event) {
        // do the necessary work
    }

    @EventListener
    public void processSessionDestroyedEvent(SessionDestroyedEvent event) {
        // do the necessary work
    }

    @EventListener
    public void processSessionExpiredEvent(SessionExpiredEvent event) {
        // do the necessary work
    }

}

Finding All Sessions of a Specific User

By retrieving all sessions of a specific user, you can track the user’s active sessions across devices or browsers. For example, you can use this information session management purposes, such as allowing the user to invalidate or logout from specific sessions or performing actions based on the user’s session activity.

To do that, first you must be using the indexed repository, and then you can inject the FindByIndexNameSessionRepository interface, like so:

@Autowired
public FindByIndexNameSessionRepository<? extends Session> sessions;

public Collection<? extends Session> getSessions(Principal principal) {
    Collection<? extends Session> usersSessions = this.sessions.findByPrincipalName(principal.getName()).values();
    return usersSessions;
}

public void removeSession(Principal principal, String sessionIdToDelete) {
    Set<String> usersSessionIds = this.sessions.findByPrincipalName(principal.getName()).keySet();
    if (usersSessionIds.contains(sessionIdToDelete)) {
        this.sessions.deleteById(sessionIdToDelete);
    }
}

In the example above, you can use the getSessions method to find all sessions of a specific user, and the removeSession method to remove a specific session of a user.