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

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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.

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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.

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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

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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

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When NOT to Use This Skill

• Distributed caching - Use spring-data-redis
• Redis operations - Use redis skill
• Session storage - Use Spring Session

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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

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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

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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

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Reference Files

File	Content
managers.md	Caffeine, Redis, EhCache, Key Generators
advanced.md	Multi-Level, Metrics, Sync, Testing

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External Documentation

• Spring Cache Abstraction
• Spring Boot Caching
• Caffeine