Working with Caching
1. Enabling Caching Support (@EnableCaching)
| Auto-detected providers | If on classpath |
|---|---|
| Caffeine | com.github.ben-manes.caffeine:caffeine |
| Redis | spring-boot-starter-data-redis |
| Hazelcast | com.hazelcast:hazelcast |
| Simple (default) | ConcurrentHashMap-based |
2. Using @Cacheable for Method Results
Example: Cache method result with condition
@Service
public class ProductService {
@Cacheable(value="products", key="#id", unless="#result == null")
public Product byId(Long id) { /* heavy lookup */ }
}3. Using @CachePut for Cache Updates
| Annotation | Effect |
|---|---|
@Cacheable |
Skip method if cache hit |
@CachePut |
Always run, store result |
@CacheEvict |
Remove entries |
@Caching |
Combine multiple |
4. Using @CacheEvict for Cache Removal
Example: Evict by key and clear all entries
@CacheEvict(value="products", key="#p.id")
public Product update(Product p) { return repo.save(p); }
@CacheEvict(value="products", allEntries=true)
public void purge() {}5. Configuring Cache Names and Keys
| Attribute | Description |
|---|---|
value/cacheNames |
Logical cache(s) |
key |
SpEL key expression |
keyGenerator |
Custom KeyGenerator bean |
condition |
SpEL — cache when true |
unless |
SpEL — skip when true (sees result) |
6. Using SpEL in Cache Annotations
| Variable | Meaning |
|---|---|
#argName |
Method argument by name |
#a0 / #p0 |
By index |
#root.method |
Method object |
#result |
Method return (post-execution only) |
@beanName.method() |
Reference other beans |
7. Configuring Simple Cache Provider
Example: Simple in-memory cache configuration
spring:
cache:
type: simple
cache-names: [products, users, sessions]8. Integrating Redis Cache
Example: Redis cache with TTL and JSON serializer
@Bean
RedisCacheConfiguration cacheConfig() {
return RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofMinutes(10))
.disableCachingNullValues()
.serializeValuesWith(SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));
}Example: Redis cache type and connection
spring:
cache: { type: redis }
data:
redis: { host: localhost, port: 6379 }9. Integrating Caffeine Cache
Example: Caffeine cache with size and expiry spec
spring:
cache:
type: caffeine
caffeine:
spec: maximumSize=10000,expireAfterWrite=10m,recordStats10. Configuring Cache Expiration and TTL
| Provider | TTL Mechanism |
|---|---|
| Redis | RedisCacheConfiguration.entryTtl() per cache |
| Caffeine | expireAfterWrite / expireAfterAccess |
| Simple | None (no expiry) |
11. Using @Caching for Multiple Operations
Example: Combined cache put and evict
@Caching(
put = { @CachePut(value="byId", key="#u.id"),
@CachePut(value="byEmail", key="#u.email") },
evict = { @CacheEvict(value="all", allEntries=true) }
)
public User save(User u) { return repo.save(u); }12. Implementing Custom Cache Manager
Example: Two-level Caffeine + Redis cache manager
@Bean
CacheManager twoLevel(RedisConnectionFactory rcf) {
CaffeineCacheManager local = new CaffeineCacheManager("hot");
local.setCaffeine(Caffeine.newBuilder().expireAfterWrite(Duration.ofMinutes(1)));
RedisCacheManager remote = RedisCacheManager.create(rcf);
return new CompositeCacheManager(local, remote);
}