Master Spring Boot 3 Caching: 8 Powerful Techniques & Real-World Examples

Introduction

Spring Boot's annotation‑driven cache mechanism can dramatically improve performance. This article presents eight practical caching techniques, covering common annotations, multi‑level caches, TTL, conditional caching, and asynchronous refresh.

1. @Cacheable

Cache the result of a method. Example:

@Cacheable(key = "#user.id", cacheNames = {"users"})
public User save(User user) {
    return user;
}

The key combines the prefix "users" with the user’s id and can be stored in Caffeine or Redis.

2. @CacheConfig

Define common cache settings at class level.

@Service
@CacheConfig(cacheNames = {"users"})
public class UserService {
    @Cacheable(key = "#user.id")
    public User save(User user) {
        return user;
    }
}

3. @CacheEvict

Remove entries from the cache.

@CacheEvict(cacheNames = "users", key = "#id")
public void deleteById(Long id) {
    System.out.printf("Deleted user [%d]%n", id);
}

To clear all entries:

@CacheEvict(cacheNames = "users", allEntries = true)
public void deleteAll() { }

4. @CachePut

Update the cache after method execution.

@CachePut(key = "#user.id")
public User updateUser(User user) {
    return user;
}

Difference from @Cacheable: @Cacheable skips method execution when the key exists, while @CachePut always runs and writes the result.

5. Custom Key Generation

Implement a KeyGenerator bean to produce complex keys.

@Bean
KeyGenerator packKeyGenerator() {
    return new KeyGenerator() {
        @Override
        public Object generate(Object target, Method method, Object... params) {
            return target.getClass().getSimpleName() + "@" + method.getName()
                   + "@" + Arrays.deepToString(params);
        }
    };
}

Use it with:

@Cacheable(keyGenerator = "packKeyGenerator")
public User save(User user) { ... }

6. Multi‑Level Cache

Combine fast in‑memory caches (Caffeine, EhCache) with Redis for scalability.

Check memory cache first.

If miss, fall back to Redis.

Only query the database when both caches miss.

Libraries such as Spring Cache abstraction + Caffeine + Redis or JetCache can implement this pattern.

7. Cache TTL (Time‑to‑Live)

Configure expiration to avoid stale data. Example for Redis:

spring:
  cache:
    type: redis
    redis:
      time-to-live: 60s

8. Conditional Caching

Cache only when a condition is met.

@Cacheable(keyGenerator = "packKeyGenerator", condition = "#user.id != 666")
public User save(User user) { ... }

Or skip caching when the result is null:

@Cacheable(unless = "#result == null")
public User save(User user) { ... }

9. Asynchronous Cache Refresh

Refresh cache periodically instead of waiting for a miss.

@Scheduled(fixedRate = 3600000)
public void refreshDictCache() {
    List<Dict> dicts = dictRepository.findAll();
    dicts.forEach(d -> cacheManager.getCache("dicts").put(d.getId(), d));
}