Spring @CacheEvict example

This is the result when we retrieve a Tutorial from cache:

Before using @CacheEvict, you update a Tutorial, for example.

Then you request the Tutorial again. If the cache TTL is not expired, the result data is not changed because the cache was not evicted.

Let’s use the Spring @CacheEvict annotation:

public class TutorialService {

  @Autowired
  TutorialRepository tutorialRepository;

  @Cacheable("tutorial")
  public Optional<Tutorial> findById(long id) {
    return tutorialRepository.findById(id);
  }

  @CacheEvict(value = "tutorial", key = "#tutorial.id")
  public Tutorial update(Tutorial tutorial) {
    return tutorialRepository.save(tutorial);
  }

  @CacheEvict(value = "tutorial", key = "#id")
  public void deleteById(long id) {
    tutorialRepository.deleteById(id);
  }
}

The TutorialService class has two methods annotated with @CacheEvict:

deleteById(long id): delete a Tutorial by id.

@CacheEvict(value = "tutorial", key = "#id")

update(Tutorial tutorial): update a Tutorial.

@CacheEvict(value = "tutorial", key = "#tutorial.id")

The key parameter specifies cache entry (key) to be evicted. It’s the Id of the Tutorial passed as a parameter.
– If the method parameter is id, the key is "#id"
– If the method parameter is tutorial, the key should be "#tutorial.id"

So when the update or deleteById method is called, Spring will remove the corresponding entry from the "tutorial" cache after the method is executed. If you want to evict cache before method invocation, set beforeInvocation to true.

The next time the findById method is called with the same id, it will execute the method and retrieve the updated data from the database, instead of returning the old data from the cache.

Now we have cache for 3 Tutorials with 3 keys:

If we run delete by id query for a specific Tutorial:

The “tutorial” cache with the key of id (tutorial::5) was evicted:

@CacheEvict with multiple keys example

Assume that we have following data in cache:

We will use @CacheEvict with multiple keys for the “tutorial”, “tutorials” and “published_tutorials” cache.

 findAll() {
    return tutorialRepository.findAll();
  }

  @Cacheable("tutorials")
  public List<Tutorial> findByTitleContaining(String title) {
    return tutorialRepository.findByTitleContaining(title);
  }

  @Cacheable("published_tutorials")
  public List<Tutorial> findByPublished(boolean isPublished) {
    return tutorialRepository.findByPublished(isPublished);
  }

  @CacheEvict(value = { "tutorial", "tutorials", "published_tutorials" }, allEntries = true)
  public void deleteAll() {
    tutorialRepository.deleteAll();
  }
}

The deleteAll method is annotated with @CacheEvict and specifies allEntries = true, which means that all entries in the “tutorial”, “tutorials”, “published_tutorials” cache will be removed when this method is called.

@CacheEvict condition example

Using @CacheEvict with condition allows you to specify a condition that must be met in order to remove the cache entry. This can be useful in scenarios where you want to selectively remove cache entries based on certain conditions, without invalidating the entire cache.

For example:

public class TutorialService {

  @Autowired
  TutorialRepository tutorialRepository;

  @CacheEvict(value = "tutorial", condition = "#tutorial.published")
  public Tutorial update(Tutorial tutorial) {
    return tutorialRepository.save(tutorial);
  }
}

The update() method is annotated with @CacheEvict and specifies a SpEL expression in the condition (#tutorial.published). This means that the cache entry will only be removed if the published property of the tutorial parameter is true. This is useful when you only want to remove entries under certain conditions, for example, when a tutorial’s status changes or when a tutorial is enabled/disabled.

Conclusion

Today you’ve known the reason why we need to evict cache, and way to use Spring @CacheEvict annotation in Spring Boot application. We also make @CacheEvict with multiple keys example.

Don’t forget to add @EnableCaching to the configuration class or service class. It enables the use of Spring’s caching abstraction in your application, allows developers to annotate methods with caching annotations such as @Cacheable and @CacheEvict.

@Service
@EnableCaching
public class TutorialService {

}

For more detail about @Cacheable annotation to tell Spring to cache the result of a method, please visit:
Spring Boot Redis Cache example

Source Code

The complete source code for this tutorial is on Github.

You can also apply the code easily on following Projects:
– Spring Boot 3 Rest API example
– Spring Boot Rest API with H2
– Spring Boot Rest API with MySQL
– Spring Boot Rest API with PostgreSQL
– Spring Boot Rest API with MongoDB
– Spring Boot Rest API with SQL Server
– Spring Boot Rest API with Cassandra
– Spring Boot Rest API with Oracle

Why we need to evict cache