Spring Boot Cache

Spring Boot Cache Abstraction

Overview

Spring Boot ships with a cache abstraction that wraps expensive service calls behind annotation-driven caches. This abstraction supports multiple cache providers (ConcurrentMap, Caffeine, Redis, Ehcache, JCache) without changing business code. The skill provides a concise workflow for enabling caching, managing cache lifecycles, and validating behavior in Spring Boot 3.5+ services.

When to Use

• Add @Cacheable, @CachePut, or @CacheEvict to Spring Boot service methods.
• Configure Caffeine, Redis, or JCache cache managers for Spring Boot.
• Diagnose cache invalidation, eviction scheduling, or cache key issues.
• Expose cache management endpoints or scheduled eviction routines.

Use trigger phrases such as "implement service caching", "configure CaffeineCacheManager", "evict caches on update", or "test Spring cache behavior" to load this skill.

Prerequisites

• Java 17+ project based on Spring Boot 3.5.x (records encouraged for DTOs).
• Dependency spring-boot-starter-cache; add provider-specific starters as needed (spring-boot-starter-data-redis, caffeine, ehcache, etc.).
• Constructor-injected services that expose deterministic method signatures.
• Observability stack (Actuator, Micrometer) when operating caches in production.

Quick Start

1. Add dependencies

   <!-- Maven -->
   <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-cache</artifactId>
   </dependency>
   <dependency> <!-- Optional: Caffeine -->
       <groupId>com.github.ben-manes.caffeine</groupId>
       <artifactId>caffeine</artifactId>
   </dependency>
   

   implementation "org.springframework.boot:spring-boot-starter-cache"
   implementation "com.github.ben-manes.caffeine:caffeine"
   

2. Enable caching

   @Configuration
   @EnableCaching
   class CacheConfig {
       @Bean
       CacheManager cacheManager() {
           return new CaffeineCacheManager("users", "orders");
       }
   }
   

3. Annotate service methods

   @Service
   @CacheConfig(cacheNames = "users")
   class UserService {
   
       @Cacheable(key = "#id", unless = "#result == null")
       User findUser(Long id) { ... }
   
       @CachePut(key = "#user.id")
       User refreshUser(User user) { ... }
   
       @CacheEvict(key = "#id", beforeInvocation = false)
       void deleteUser(Long id) { ... }
   }
   

4. Verify behavior

   • Run focused unit tests that call cached methods twice and assert repository invocations.
   • Inspect Actuator cache endpoint (if enabled) for hit/miss counters.

Implementation Workflow

1. Define Cache Strategy

• Map hot-path read operations to @Cacheable.
• Use @CachePut on write paths that must refresh cache entries.
• Apply @CacheEvict (allEntries = true when invalidating derived caches).
• Combine operations with @Caching to keep multi-cache updates consistent.

2. Shape Cache Keys and Conditions

• Generate deterministic keys via SpEL (e.g. key = "#user.id").
• Guard caching with condition = "#price > 0" for selective caching.
• Prevent null or stale values with unless = "#result == null".
• Synchronize concurrent updates via sync = true when needed.

3. Manage Providers and TTLs

• Configure provider-specific options:
  • Caffeine spec: spring.cache.caffeine.spec=maximumSize=500,expireAfterWrite=10m
  • Redis TTL: spring.cache.redis.time-to-live=600000
  • Ehcache XML: define ttl and heap/off-heap resources.
• Expose cache names via spring.cache.cache-names=users,orders,catalog.
• Avoid on-demand cache name creation in production unless metrics cover usage.

4. Operate and Observe Caches

• Surface cache maintenance via a dedicated CacheManagementService with programmatic cacheManager.getCache(name) access.
• Schedule periodic eviction for time-bound caches using @Scheduled.
• Wire Actuator cache endpoint and Micrometer meters to track hit ratio, eviction count, and size.

5. Test and Validate

• Prefer slice or unit tests with Mockito/SpyBean to ensure method invocation counts.
• Add integration tests with Testcontainers for Redis/Ehcache when using external providers.
• Validate concurrency behavior under load (e.g. sync = true scenarios).

Advanced Options

• Integrate JCache annotations when interoperating with providers that favor JSR-107 (@CacheResult, @CacheRemove). Avoid mixing with Spring annotations on the same method.
• Cache reactive return types (Mono, Flux) or CompletableFuture values. Spring stores resolved values and resubscribes on hits; consider TTL alignment with publisher semantics.
• Apply HTTP caching headers using CacheControl when exposing cached responses via REST.

Examples

• Load references/cache-examples.md for progressive scenarios (basic product cache, conditional caching, multilevel eviction, Redis integration).
• Load references/cache-core-reference.md for annotation matrices, configuration tables, and property samples.

References

• references/spring-framework-cache-docs.md: curated excerpts from the Spring Framework Reference Guide (official).
• references/spring-cache-doc-snippet.md: narrative overview extracted from Spring documentation.
• references/cache-core-reference.md: annotation parameters, dependency matrices, property catalogs.
• references/cache-examples.md: end-to-end examples with tests.

Best Practices

• Prefer constructor injection and immutable DTOs for cache entries.
• Separate cache names per aggregate (users, orders) to simplify eviction.
• Log cache hits/misses only at debug to avoid noise; push metrics via Micrometer.
• Tune TTLs based on data staleness tolerance; document rationale in code.
• Guard caches that store PII or credentials with encryption or avoid caching.
• Align cache eviction with transactional boundaries to prevent dirty reads.

Constraints and Warnings

• Avoid caching mutable entities that depend on open persistence contexts.
• Do not mix Spring cache annotations with JCache annotations on the same method.
• Ensure multi-level caches (e.g. Caffeine + Redis) maintain consistency; prefer publish/subscribe invalidation channels.
• Validate serialization compatibility when caching across service instances.
• Monitor memory footprint to prevent OOM when using in-memory stores.

Related Skills

• skills/spring-boot/spring-boot-rest-api-standards
• skills/spring-boot/spring-boot-test-patterns
• skills/junit-test/unit-test-caching

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