Complete implementation steps for Redis expiration event listener

Redis expiration event listener complete implementation

To update database status using the Redis expiration event listener, we need to make sure that Redis's event notification is enabled and implement the listener to capture expired keys and update the database as needed.

Step 1: Enable Redis Expiration Event Notification

Key event notifications need to be enabled in the Redis configuration file. You can use Redis configuration fileAdd the following configuration:

notify-keyspace-events Ex

If you run Redis using Docker, you can pass in parameters at startup:

docker run -d redis redis-server --notify-keyspace-events Ex

Step 2: Redis Expired Event Listener Code

Here is a complete Redis listener implementation that captures expired keys and updates user status:

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@Component
public class RedisExpiredListener implements MessageListener {

    @Override
    public void onMessage(Message message, byte[] pattern) {
        String expiredKey = ();
        
        // The key to determine whether it is a user information cache        if (("userInfo:")) {
            try {
                Long userId = ((":")[1]);
                updateUserStatus(userId);
            } catch (NumberFormatException e) {
                ("Resolving user ID failed:" + expiredKey);
            }
        }
    }

    /**
      * Update the user status in the database
      *
      * @param userId User ID
      */
    private void updateUserStatus(Long userId) {
        ("User" + userId + "The token has expired, updated status...");
        // TODO: Write the logic to update the database here        // Example: (userId);    }
}

Step 3: Enable Listening in Spring Boot

The Redis listener needs to be registered in the Redis connection factory.

In yourRedis configuration classThe following configuration is performed:

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@Configuration
public class RedisConfig {

    @Bean
    public RedisMessageListenerContainer redisContainer(RedisConnectionFactory connectionFactory,
                                                        RedisExpiredListener expiredListener) {
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        (connectionFactory);
        
        // Listen to all key space events (including expired events)        (expiredListener, new ChannelTopic("__keyevent@0__:expired"));
        
        return container;
    }
}

Step 4: Sample database update logic

In the listener, you can call the user service (userService) to update the user status in the database:

@Autowired
private UserService userService;

private void updateUserStatus(Long userId) {
    ("User" + userId + "The token has expired, updated status...");
    (userId);
}

existUserServiceImplement status update:

@Service
public class UserService {

    public void updateUserStatusToExpired(Long userId) {
        //Update the user status in the database to expired        ("User is being transferred" + userId + "The status of the update to expired...");
        // Perform database update operations (such as using MyBatis or JPA)    }
}

Summarize

Enable Redis key event notification: Make sure that Redis configuration is enablednotify-keyspace-events ExOptions.
Implementing Redis listener: Capture expired events and update user status.
Register the listener to the Spring container:passRedisMessageListenerContainerExpiration event of the listen key.
Update database status: Call service layer logic in the listener to complete database update.

In this way, when the user cache key in Redis expires, the listener will automatically fire and update the user status in the database.

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