Default Cache Manager with Spring Boot using @EnableCaching

Question

I have implemented caching in my SpringBootApplication as shown below

@SpringBootApplication
@EnableCaching
public class SampleApplication extends SpringBootServletInitializer {

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(SampleApplication.class);
    }

    public static void main(String[] args) {
        SpringApplication.run(SampleApplication.class, args);
    }

This is absolutely working fine.

But to implement caching there should be one mandatory CacheManager / Cacheprovider defined. Without defining any cacheManager also my application is working fine.

Is there any default Cache manager defined by Spring ? Spring docs says Spring Boot auto-configures a suitable CacheManager.

So what will be CacheManager used if we do not define it ?

Answer 1

The Spring Boot starter provides a simple cache provider which stores values in an instance of ConcurrentHashMap. This is the simplest possible thread-safe implementation of the caching mechanism.

If the @EnableCaching annotation is present in your app, Spring Boot checks dependencies available on your class path and configures an appropriate CacheManager. Depending on a chosen provider, some additional configuration may be required. You can find all information about configuration in the first link from this answer.

Answer 2

If you want to define explicitly (from any reason) the simplest cache manager (which uses ConcurrentHashMap under the hood), please do:

@Bean
public CacheManager cacheManager() {
    return new org.springframework.cache.concurrent.ConcurrentMapCacheManager();
}