How do you configure cache settings in Spring Boot?

Table of Contents

• Introduction
• Setting Up Cache in Spring Boot
  • Step 1: Add Caching Dependencies
  • Step 2: Enable Caching
• Configuring Cache Providers
  • Configuring Simple In-Memory Cache (ConcurrentMapCache)
    • Configure In-Memory Cache in application.properties:
  • Configuring Redis as Cache Provider
    • Configure Redis in application.properties:
    • Example Redis Cache Configuration:
  • Configuring EhCache
• Customizing Cache Settings
  • Step 3: Set Cache Expiry (TTL) for Cache Entries
    • Configure TTL for Redis Cache (Example):
  • Step 4: Use Cache Configuration Properties
    • Example for Redis TTL in application.properties:
  • Step 5: Use @Cacheable to Cache Method Results
    • Example using @Cacheable:
  • Step 6: Cache Eviction with @CacheEvict
• Conclusion

Introduction

Caching is a crucial part of optimizing the performance of web applications. In Spring Boot, caching can be easily configured to improve the speed and reduce the load on backend systems such as databases or external APIs. Proper configuration allows you to fine-tune how caches are created, managed, and evicted. In this guide, we will explore how to configure cache settings in Spring Boot, including configuring cache providers, setting cache expiration, and customizing cache behavior with a custom cache manager.

Setting Up Cache in Spring Boot

Step 1: Add Caching Dependencies

To start using caching in a Spring Boot application, you need to include the necessary dependencies in your pom.xml file (for Maven projects).

• **spring-boot-starter-cache**: This starter enables Spring Boot’s caching abstraction.
• **spring-boot-starter-data-redis**: If you're using Redis as a cache provider, this starter is required to integrate Redis with your application.

Step 2: Enable Caching

To enable caching in your Spring Boot application, add the @EnableCaching annotation to a configuration class.

• **@EnableCaching**: This annotation enables the caching mechanism and activates caching annotations like @Cacheable, @CacheEvict, and @CachePut across the Spring context.

Configuring Cache Providers

Spring Boot supports multiple cache providers, and you can configure a cache provider based on your use case. Common cache providers include Redis, EhCache, Caffeine, and Simple Map.

Configuring Simple In-Memory Cache (ConcurrentMapCache)

By default, Spring Boot configures a simple in-memory cache provider (using ConcurrentMapCacheManager). You can use this for quick prototyping and small applications that don’t require distributed cache solutions.

Configure In-Memory Cache in application.properties:

This uses Spring's default ConcurrentMapCacheManager with no external cache provider. Cache entries will reside in memory only.

Configuring Redis as Cache Provider

Redis is a popular choice for distributed caching. To use Redis, you need to add the spring-boot-starter-data-redis dependency (as shown above) and configure Redis in your application’s application.properties or application.yml.

Configure Redis in application.properties:

Example Redis Cache Configuration:

• **RedisCacheManager**: It manages Redis-based caches in your application. You can customize its behavior by setting options such as TTL (Time to Live), key serialization, etc.

Configuring EhCache

EhCache is another popular cache provider that is often used for more complex caching scenarios, especially for local, in-process caching. To use EhCache in Spring Boot, you need to add the spring-boot-starter-cache and ehcache dependencies.

Then, configure EhCache in your application.properties or application.yml:

You also need to provide an ehcache.xml configuration file for cache settings.

Customizing Cache Settings

Step 3: Set Cache Expiry (TTL) for Cache Entries

You can configure cache expiration settings such as Time to Live (TTL) to define how long cached data should remain before being evicted.

Configure TTL for Redis Cache (Example):

• **entryTtl(Duration.ofMinutes(5))**: This specifies that the cache entry should expire after 5 minutes.
• **disableCachingNullValues()**: This prevents caching of null values, which could happen when the data is not found.

Step 4: Use Cache Configuration Properties

You can also set cache properties such as maximum size and expiration directly through application.properties (for specific providers like Redis).

Example for Redis TTL in application.properties:

Step 5: Use @Cacheable to Cache Method Results

Once caching is configured, you can use annotations like @Cacheable, @CacheEvict, and @CachePut to interact with the cache.

Example using @Cacheable:

• **@Cacheable**: This annotation caches the result of the method based on the provided cache name (value) and the cache key (key).
• Cache Expiry: The cache entry for the getProductById method will respect the TTL you set in the configuration (e.g., 5 minutes).

Step 6: Cache Eviction with @CacheEvict

You may want to clear or evict cached entries after certain actions, such as updating or deleting data.

• **@CacheEvict**: This annotation removes the cached entry for a specific key (productId) when the method is invoked.

Conclusion

Configuring cache settings in Spring Boot is an essential step in optimizing application performance by reducing redundant operations like database queries and expensive computations. Spring Boot offers various cache providers, including Redis, EhCache, and the default in-memory cache. By configuring TTL, cache expiration, and custom cache managers, you can effectively control how data is cached and managed in your application.

Remember, the proper configuration of cache expiration, eviction policies, and cache providers ensures that your application performs optimally without overloading memory or returning stale data.