Spring Cache

Quick Start

@SpringBootApplication @EnableCaching public class Application {}

@Service public class UserService {

@Cacheable("users")
public User findById(Long id) {
    return userRepository.findById(id).orElseThrow();
}

@CacheEvict(value = "users", key = "#id")
public void deleteUser(Long id) {
    userRepository.deleteById(id);
}

}

spring: cache: type: caffeine caffeine: spec: maximumSize=1000,expireAfterWrite=10m

Cache Annotations

@Cacheable

@Cacheable("products") public Product findById(Long id) { }

@Cacheable(value = "products", key = "#category + '-' + #status") public List<Product> findByCategoryAndStatus(String category, String status) { }

@Cacheable(value = "products", condition = "#id > 0") public Product findByIdConditional(Long id) { }

@Cacheable(value = "products", unless = "#result == null") public Product findByIdUnlessNull(Long id) { }

@Cacheable(value = "products", sync = true) // One thread populates public Product findByIdSync(Long id) { }

@CacheEvict

@CacheEvict(value = "products", key = "#id") public void deleteProduct(Long id) { }

@CacheEvict(value = "products", allEntries = true) public void clearProductCache() { }

@CacheEvict(value = "products", key = "#id", beforeInvocation = true) public void deleteProductBeforeInvocation(Long id) { }

@CachePut

@CachePut(value = "products", key = "#product.id") public Product saveProduct(Product product) { return productRepository.save(product); }

@CachePut(value = "products", key = "#result.id") public Product createProduct(CreateProductRequest request) { return productRepository.save(new Product(request)); }

@Caching (Multiple Operations)

@Caching( put = { @CachePut(value = "products", key = "#result.id"), @CachePut(value = "productsBySku", key = "#result.sku") }, evict = { @CacheEvict(value = "productList", allEntries = true) } ) public Product createProduct(CreateProductRequest request) { }

@CacheConfig (Class-Level)

@Service @CacheConfig(cacheNames = "products", keyGenerator = "customKeyGenerator") public class ProductService {

@Cacheable  // Uses class config
public Product findById(Long id) { }

@Cacheable(cacheNames = "inventory")  // Override cache name
public Inventory getInventory(Long productId) { }

}

Full Reference: See managers.md for Caffeine, Redis, EhCache configurations.

Quick Cache Manager Setup

Caffeine (Single Instance)

@Bean public CacheManager cacheManager() { CaffeineCacheManager manager = new CaffeineCacheManager(); manager.setCaffeine(Caffeine.newBuilder() .maximumSize(10_000) .expireAfterWrite(Duration.ofMinutes(10)) .recordStats()); return manager; }

Redis (Distributed)

@Bean public CacheManager cacheManager(RedisConnectionFactory factory) { RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig() .entryTtl(Duration.ofMinutes(10)) .serializeValuesWith(SerializationPair .fromSerializer(new GenericJackson2JsonRedisSerializer()));

return RedisCacheManager.builder(factory)
    .cacheDefaults(config)
    .build();

}

Full Reference: See advanced.md for Multi-Level Caching, Metrics, Synchronization.

Best Practices

Do Don't

Use Caffeine for single-instance Skip TTL configuration

Use Redis for distributed Cache mutable objects

Configure TTL always Ignore cache eviction

Use sync=true for expensive ops Use high cardinality keys

Implement cache metrics Cache sensitive data unencrypted

Production Checklist

• Cache provider configured (Caffeine/Redis)

• TTL configured for every cache

• Cache eviction on write operations

• Metrics configured

• Serialization tested

• Distributed lock for critical ops

When NOT to Use This Skill

• Distributed caching - Use spring-data-redis

• Redis operations - Use redis skill

• Session storage - Use Spring Session

Common Pitfalls

Error Cause Solution

Cache not working Internal call (same bean) Use self-injection

Null pointer Null values cached Use unless = "#result == null"

Memory leak TTL not configured Set expireAfterWrite

Serialization error Non-serializable objects Implement Serializable

Anti-Patterns

Anti-Pattern Problem Solution

Caching mutable objects Stale data Cache immutable data

No TTL configured Stale cache forever Set expireAfterWrite

@Cacheable on void No effect Only cache with return

No cache sync Race conditions Use sync=true or locks

Quick Troubleshooting

Problem Diagnostic Fix

Cache not working Check @EnableCaching Add annotation

Wrong data cached Check cache key Define explicit key

Cache not evicted Check key expression Verify key matches

Self-invocation bypass Same class call Inject self

Reference Files

File Content

managers.md Caffeine, Redis, EhCache, Key Generators

advanced.md Multi-Level, Metrics, Sync, Testing

External Documentation

• Spring Cache Abstraction

• Spring Boot Caching

• Caffeine