How do you create a custom cache manager in Spring Boot?

Table of Contents

• Introduction
• Steps to Create a Custom Cache Manager in Spring Boot
  • Step 1: Add Dependencies for Caching
    • For Maven:
    • For Gradle:
  • Step 2: Implement a Custom Cache Manager
    • Example: Creating a Simple Custom Cache Manager
    • Example: Implementing a Custom Cache with Expiration Logic
  • Step 3: Use the Custom Cache Manager in Your Application
    • Example: Using @Cacheable with Custom Cache Manager
  • Step 4: Test Your Custom Cache Manager
    • Example: Testing Caching in Controller
• Conclusion

Introduction

In a Spring Boot application, caching can significantly improve the performance by storing frequently accessed data in memory, reducing the need for repeated calls to the database or other slow operations. While Spring Boot provides default cache managers, you might have specific needs that require a custom cache manager. A custom cache manager allows you to tailor the caching behavior to your application’s requirements, such as implementing custom eviction policies, cache size limits, or integrating with an external caching system.

This guide will walk you through how to create and configure a custom cache manager in Spring Boot.

Steps to Create a Custom Cache Manager in Spring Boot

Step 1: Add Dependencies for Caching

First, you need to ensure that you have the necessary dependencies for caching support in your Spring Boot application. These dependencies include the core spring-boot-starter-cache and any additional cache provider you want to use (e.g., EhCache, Redis, or in-memory caching).

For Maven:

For Gradle:

Step 2: Implement a Custom Cache Manager

Spring Boot provides a flexible caching framework, and you can define your own cache manager by extending the CacheManager interface or configuring a custom CacheManager bean.

Example: Creating a Simple Custom Cache Manager

In this example, we will create a custom cache manager that uses a ConcurrentHashMap for storing cached data. This is a basic in-memory cache manager, but it can be extended for more complex needs.

• In this configuration, ConcurrentMapCacheManager is used, which is a simple in-memory cache implementation.
• The setCacheNames method is used to define the cache names for this custom cache manager (in this case, "customCache").

Example: Implementing a Custom Cache with Expiration Logic

You can create a custom cache that implements expiration logic based on time-to-live (TTL) for cache entries.

In this example:

• The CustomCache class manages a cache with TTL (time-to-live). If an entry is older than 5 seconds, it will be removed.
• The CacheManager interface is implemented with a ConcurrentHashMap that stores caches by name.

Step 3: Use the Custom Cache Manager in Your Application

Once you've configured the custom cache manager, you can use it with Spring’s caching annotations like @Cacheable, @CachePut, and @CacheEvict.

Example: Using @Cacheable with Custom Cache Manager

In this example:

• The @Cacheable annotation uses the cache named "customCache" defined in the custom cache manager.
• The method getProductById will have its result cached in the custom cache, and subsequent calls will return the cached value.

Step 4: Test Your Custom Cache Manager

You can test the caching functionality by calling methods with the same parameters multiple times and observing how the results are cached.

Example: Testing Caching in Controller

• When the /product/{id} endpoint is called multiple times with the same id, the response should be cached, and the second and subsequent calls should be faster.

Conclusion

Creating a custom cache manager in Spring Boot allows you to tailor caching behavior according to the specific needs of your application. Whether you want to implement a custom eviction policy, use a specific caching strategy, or integrate with an external caching provider, Spring Boot offers flexibility to build a custom caching solution.

By defining your cache manager, implementing the Cache interface, and using caching annotations such as @Cacheable, you can efficiently manage data caching and enhance the performance of your Spring Boot applications.