How do you create a custom caching implementation in Spring Boot?

Table of Contents

• Introduction
• Steps to Create a Custom Caching Implementation in Spring Boot
  • 1. Define a Custom Cache Implementation
  • 2. Create a Custom Cache Manager
  • 3. Integrate the Custom Cache Manager into Spring Boot
  • 4. Use Caching Annotations with Custom Caching
  • 5. Custom Cache Eviction
  • 6. Test Your Custom Cache Implementation
• Conclusion

Introduction

While Spring Boot provides built-in support for common caching providers like Redis, Ehcache, and ConcurrentMap, there may be scenarios where you need a custom caching implementation tailored to your specific requirements. This could be due to the need for custom eviction policies, a specialized storage mechanism, or integrating with a unique data source.

In this guide, we’ll walk through the steps to create a custom caching implementation in Spring Boot, including implementing your own CacheManager, creating a custom Cache provider, and integrating it into your Spring Boot application.

Steps to Create a Custom Caching Implementation in Spring Boot

1. Define a Custom Cache Implementation

In order to create custom caching logic, you need to define a custom Cache class that will handle cache storage, retrieval, eviction, and other operations.

Here’s an example of a simple custom Cache implementation:

In this example, we create a custom Cache that uses a ConcurrentHashMap to store cache entries. The cache provides basic operations such as get(), put(), evict(), and clear().

2. Create a Custom Cache Manager

Next, you need to create a custom CacheManager implementation that will handle the management and retrieval of custom caches. The CacheManager is responsible for creating and returning cache instances.

Here’s an example of a simple CacheManager implementation:

In this example, the CustomCacheManager stores caches in a Map<String, Cache>. It lazily creates new cache instances using the CustomCache class when requested. The getCacheNames() method returns the list of cache names.

3. Integrate the Custom Cache Manager into Spring Boot

Once you've defined your custom Cache and CacheManager, you need to register the custom cache manager with Spring Boot’s caching system. You can do this by defining a CacheManager bean in a configuration class.

Here’s how you can integrate your custom cache manager:

By annotating the configuration class with @EnableCaching, Spring Boot will enable the caching abstraction and use the CacheManager bean (our custom CacheManager) for managing caches.

4. Use Caching Annotations with Custom Caching

Now that your custom caching setup is in place, you can use the caching annotations such as @Cacheable, @CachePut, and @CacheEvict in your services or controllers, just like you would with any other cache provider.

Here’s an example of how you can use caching in a service class:

In this example, the getUser method is annotated with @Cacheable, which will cache the result of the method call in the custom cache named "users". When the method is called with the same id argument again, the cached value will be returned.

5. Custom Cache Eviction

You can also define custom cache eviction logic if needed. For example, you might want to implement time-based eviction or size-based eviction. Here’s how you can modify your CustomCache class to implement a simple time-to-live (TTL) eviction:

In this modified CustomCache, each cache entry stores a timestamp, and the cache checks whether an entry has expired based on the TTL value. If an entry is expired, it is removed from the cache.

6. Test Your Custom Cache Implementation

Once everything is set up, test your custom caching implementation to ensure that caching works as expected. You can add test cases to check cache hits, evictions, and TTL functionality.

Conclusion

Creating a custom caching implementation in Spring Boot allows you to tailor caching behavior to your application's specific needs. By implementing your own Cache and CacheManager, you can control cache storage, eviction policies, and integration with other systems. This approach provides the flexibility to design a caching solution that suits your use case, whether you need in-memory caches, distributed caches, or custom eviction strategies. With the @Cacheable, @CachePut, and @CacheEvict annotations, integrating custom caching seamlessly into your Spring Boot application is simple and efficient.