What is the purpose of the @CacheConfig annotation?

Introduction
6. Conclusion

Introduction

In Spring, caching allows you to store method results and reuse them to improve performance by avoiding repeated calculations. Spring provides several ways to configure caching in an application, and one of those ways is through the @CacheConfig annotation. This annotation is used to simplify and centralize caching configurations when multiple cacheable methods within a class need to share common caching settings.

The @CacheConfig annotation allows developers to specify cache-related configurations that are applied to all methods within the class, making it easier to maintain and reduce redundancy. This is particularly useful when multiple methods in a service or component share the same cache names, expiration policies, or other configurations.

1. What Does `@CacheConfig` Do?

The @CacheConfig annotation is used at the class level in Spring. It allows you to define default cache settings for all cacheable methods in that class, such as specifying the default cache name, key generation strategy, and other cache-related properties.

When applied, it eliminates the need to repeat cache configuration on each individual method. For example, instead of specifying the same cache name or expiration time on each method, you can define these settings once at the class level using @CacheConfig.

2. Usage of `@CacheConfig`

Basic Example:

Here's an example of how to use @CacheConfig:

In this example:

The @CacheConfig annotation is applied at the class level with a cacheNames attribute. This means that both methods in the ProductService class will use the "products" cache by default.
The @Cacheable annotations on both getProductById and getProductsByCategory will refer to the "products" cache defined in the @CacheConfig annotation.
The key for each method can still be defined individually to customize how caching is performed for each method.

3. Attributes of `@CacheConfig`

@CacheConfig comes with several useful attributes that allow you to configure caching behavior in a more granular way:

**cacheNames**: Specifies the names of the caches to be used. This is the most commonly used attribute. If not provided at the method level, Spring will use this default value.
**keyGenerator**: Specifies the bean name of a custom KeyGenerator to generate cache keys. This is useful if you want to control how cache keys are generated for methods in this class.
**cacheManager**: Specifies the cache manager to be used for caching. This is useful when you have multiple cache managers and need to select one.
**condition**: Allows setting a SpEL (Spring Expression Language) expression to define when to cache a result. This can be used to apply cache only under certain conditions.
**unless**: Similar to condition, but it specifies when to skip caching the result. It can be useful for caching only when certain conditions are met.

4. Benefits of Using `@CacheConfig`

a. Simplifies Cache Configuration

By using @CacheConfig, you reduce the need to repeat common caching properties across methods. This can significantly reduce redundancy in your code, especially if multiple methods within a class share the same cache configuration.

b. Centralized Cache Configuration

Instead of configuring cache names, key generation strategies, or other properties on every single method, you can centralize this configuration at the class level. This makes the caching logic more consistent and easier to manage across different methods.

c. Improved Maintainability

If you need to modify cache-related settings, you only need to do it in one place — at the class level. This improves the maintainability of your code, as any change to cache configuration doesn't require you to modify each method individually.

5. Practical Example: Applying CacheConfig for Multiple Methods

Here's a scenario where using @CacheConfig can improve the readability and maintainability of your code.

Example: ProductService with Multiple Cacheable Methods