Comprehensive Guide to Setting Up Redis Caching in Spring Boot

Caching is a powerful technique to improve the performance and scalability of your application. In this guide, we will walk through how to configure Redis for caching in a Spring Boot application. We will explore the required dependencies, YAML configuration, and how to apply caching annotations to your services.

🔧 Required Dependencies

To enable Redis caching in a Spring Boot application, make sure to include the following dependencies in your project:

Maven (pom.xml):

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
    </dependency>
</dependencies>

⚙️ Configuring Redis for Caching

In order to use Redis effectively, you need to configure how values are serialized and cached.

Java Configuration Class:

@Configuration
@EnableCaching // Enables Spring's annotation-driven cache management
public class CacheConfig {
 
    @Bean
    public RedisCacheConfiguration cacheConfiguration() {
        return RedisCacheConfiguration.defaultCacheConfig()
            .serializeValuesWith(
                RedisSerializationContext.SerializationPair.fromSerializer(
                    new GenericJackson2JsonRedisSerializer()));
    }
}

• @EnableCaching enables annotation-based caching.
• GenericJackson2JsonRedisSerializer is used to serialize values to JSON, ensuring readability and compatibility.

🛠️ Configuring application.yml for Redis Caching

Ensure your application.yml file specifies that Redis is the caching provider:

spring:
  cache:
    type: redis
  redis:
    host: localhost
    port: 6379

You may also want to configure Redis connection timeout, password, and other pool settings if you're running in production.

💡 Using @Cacheable and @CacheEvict in Services

Spring provides a set of annotations to simplify cache usage.

@Cacheable – Cache Method Results

Use @Cacheable when you want to cache the result of a method. Spring will check the cache first before executing the method.

@Service
@RequiredArgsConstructor
public class UserCacheService {
 
    private final UserRepository userRepository;
    private final UserCacheDTOMapper userCacheDTOMapper;
 
    @Cacheable(value = "userById", key = "#id", unless = "#result == null")
    public UserCacheDTO getUserById(Long id) {
        return userCacheDTOMapper.toUserCacheDTO(
            userRepository.findById(id).orElse(null)
        );
    }
}

Explanation:

• value = "userById" defines the cache name.
• key = "#id" tells Spring to use the id as the key.
• unless = "#result == null" prevents caching if the result is null.

@CacheEvict – Invalidate Cache When Data Changes

Use @CacheEvict to remove entries from the cache when the data is modified.

@Caching(evict = {
    @CacheEvict(value = "userByUsername", key = "#username"),
    @CacheEvict(value = "userExistsByUsername", key = "#username")
})
public void createUser(String username, String password, Role role) {
    userRepository.save(new User(username, password, role));
}

Explanation:

• This example removes related cache entries when a new user is created to prevent stale data.

✅ Summary

By following this guide, you have:

• Integrated the required dependencies for Redis caching in Spring Boot.
• Configured Redis and serialization for proper caching behavior.
• Applied @Cacheable and @CacheEvict annotations to cache and invalidate data effectively.

Caching with Redis is a great way to improve the performance of your application, especially in microservices and data-intensive systems. It minimizes database hits and increases response time.

💻 Pro Tips

• Consider using @CachePut if you want to update the cache without evicting it.
• Use a Time-to-Live (TTL) on your Redis keys for automatic expiration.

📌 Real-World Usage

This Kafka configuration is part of the actual implementation of the Chat Service.

✍️ Author

Le Minh Duc A passionate Java & Spring developer building scalable microservices.