gh-giuseppe-trisciuoglio-developer-kit-developer-kit/skills/spring-boot-cache/references/spring-cache-doc-snippet.md

The Spring Framework provides support for transparently adding caching to an application. At its core, the abstraction applies caching to methods, thus reducing the number of executions based on the information available in the cache. The caching logic is applied transparently, without any interference to the invoker. Spring Boot auto-configures the cache infrastructure as long as caching support is enabled by using the org.springframework.cache.annotation.EnableCaching[format=annotation] annotation.

Note

Check the {url-spring-framework-docs}/integration/cache.html[relevant section] of the Spring Framework reference for more details.

In a nutshell, to add caching to an operation of your service add the relevant annotation to its method, as shown in the following example:

include-code::MyMathService[]

This example demonstrates the use of caching on a potentially costly operation. Before invoking computePiDecimal, the abstraction looks for an entry in the piDecimals cache that matches the precision argument. If an entry is found, the content in the cache is immediately returned to the caller, and the method is not invoked. Otherwise, the method is invoked, and the cache is updated before returning the value.

Caution

You can also use the standard JSR-107 (JCache) annotations (such as javax.cache.annotation.CacheResult[format=annotation]) transparently. However, we strongly advise you to not mix and match the Spring Cache and JCache annotations.

If you do not add any specific cache library, Spring Boot auto-configures a simple provider that uses concurrent maps in memory. When a cache is required (such as piDecimals in the preceding example), this provider creates it for you. The simple provider is not really recommended for production usage, but it is great for getting started and making sure that you understand the features. When you have made up your mind about the cache provider to use, please make sure to read its documentation to figure out how to configure the caches that your application uses. Nearly all providers require you to explicitly configure every cache that you use in the application. Some offer a way to customize the default caches defined by the configprop:spring.cache.cache-names[] property.

Tip

It is also possible to transparently {url-spring-framework-docs}/integration/cache/annotations.html#cache-annotations-put[update] or {url-spring-framework-docs}/integration/cache/annotations.html#cache-annotations-evict[evict] data from the cache.

Supported Cache Providers

The cache abstraction does not provide an actual store and relies on abstraction materialized by the org.springframework.cache.Cache[] and org.springframework.cache.CacheManager[] interfaces.

If you have not defined a bean of type org.springframework.cache.CacheManager[] or a org.springframework.cache.interceptor.CacheResolver[] named cacheResolver (see `org.springframework.cache.annotation.CachingConfigurer[]), Spring Boot tries to detect the following providers (in the indicated order):

1. io/caching.xml

2. io/caching.xml (EhCache 3, Hazelcast, Infinispan, and others)

3. io/caching.xml

4. io/caching.xml

5. io/caching.xml

6. io/caching.xml

7. io/caching.xml

8. io/caching.xml

9. io/caching.xml

Additionally, {url-spring-boot-for-apache-geode-site}[Spring Boot for Apache Geode] provides {url-spring-boot-for-apache-geode-docs}#geode-caching-provider[auto-configuration for using Apache Geode as a cache provider].

Tip

If the `org.springframework.cache.CacheManager[] is auto-configured by Spring Boot, it is possible to force a particular cache provider by setting the configprop:spring.cache.type[] property. Use this property if you need to use no-op caches in certain environments (such as tests).

Tip

Use the spring-boot-starter-cache starter to quickly add basic caching dependencies. The starter brings in spring-context-support. If you add dependencies manually, you must include spring-context-support in order to use the JCache or Caffeine support.

If the org.springframework.cache.CacheManager[] is auto-configured by Spring Boot, you can further tune its configuration before it is fully initialized by exposing a bean that implements the org.springframework.boot.autoconfigure.cache.CacheManagerCustomizer[] interface. The following example sets a flag to say that null values should not be passed down to the underlying map:

include-code::MyCacheManagerConfiguration[]

Note

In the preceding example, an auto-configured org.springframework.cache.concurrent.ConcurrentMapCacheManager[] is expected. If that is not the case (either you provided your own config or a different cache provider was auto-configured), the customizer is not invoked at all. You can have as many customizers as you want, and you can also order them by using org.springframework.core.annotation.Order[format=annotation] or org.springframework.core.Ordered[].

Generic

Generic caching is used if the context defines at least one org.springframework.cache.Cache[] bean. A org.springframework.cache.CacheManager[] wrapping all beans of that type is created.

JCache (JSR-107)

JCache is bootstrapped through the presence of a javax.cache.spi.CachingProvider[] on the classpath (that is, a JSR-107 compliant caching library exists on the classpath), and the org.springframework.cache.jcache.JCacheCacheManager[] is provided by the spring-boot-starter-cache starter. Various compliant libraries are available, and Spring Boot provides dependency management for Ehcache 3, Hazelcast, and Infinispan. Any other compliant library can be added as well.

It might happen that more than one provider is present, in which case the provider must be explicitly specified. Even if the JSR-107 standard does not enforce a standardized way to define the location of the configuration file, Spring Boot does its best to accommodate setting a cache with implementation details, as shown in the following example:

    # Only necessary if more than one provider is present
    spring:
      cache:
        jcache:
          provider: "com.example.MyCachingProvider"
          config: "classpath:example.xml"

Note

When a cache library offers both a native implementation and JSR-107 support, Spring Boot prefers the JSR-107 support, so that the same features are available if you switch to a different JSR-107 implementation.

Tip

Spring Boot has general support for Hazelcast. If a single com.hazelcast.core.HazelcastInstance[] is available, it is automatically reused for the javax.cache.CacheManager[] as well, unless the configprop:spring.cache.jcache.config[] property is specified.

There are two ways to customize the underlying `javax.cache.CacheManager[]:

• Caches can be created on startup by setting the configprop:spring.cache.cache-names[] property. If a custom `javax.cache.configuration.Configuration[] bean is defined, it is used to customize them.

• org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer[] beans are invoked with the reference of the javax.cache.CacheManager[] for full customization.

Tip

If a standard javax.cache.CacheManager[] bean is defined, it is wrapped automatically in an org.springframework.cache.CacheManager[] implementation that the abstraction expects. No further customization is applied to it.

Hazelcast

Spring Boot has general support for Hazelcast. If a com.hazelcast.core.HazelcastInstance[] has been auto-configured and com.hazelcast:hazelcast-springis on the classpath, it is automatically wrapped in aorg.springframework.cache.CacheManager[].

Note

Hazelcast can be used as a JCache compliant cache or as a Spring org.springframework.cache.CacheManager[] compliant cache. When setting configprop:spring.cache.type[] to hazelcast, Spring Boot will use the org.springframework.cache.CacheManager[] based implementation. If you want to use Hazelcast as a JCache compliant cache, set configprop:spring.cache.type[] to jcache. If you have multiple JCache compliant cache providers and want to force the use of Hazelcast, you have to explicitly set the JCache provider.

Infinispan

Infinispan has no default configuration file location, so it must be specified explicitly. Otherwise, the default bootstrap is used.

spring:
  cache:
    infinispan:
      config: "infinispan.xml"

Caches can be created on startup by setting the configprop:spring.cache.cache-names[] property. If a custom `org.infinispan.configuration.cache.ConfigurationBuilder[] bean is defined, it is used to customize the caches.

To be compatible with Spring Boot’s Jakarta EE 9 baseline, Infinispan’s -jakarta modules must be used. For every module with a -jakarta variant, the variant must be used in place of the standard module. For example, infinispan-core-jakarta and infinispan-commons-jakarta must be used in place of infinispan-core and infinispan-commons respectively.

Couchbase

If Spring Data Couchbase is available and Couchbase is configured, a org.springframework.data.couchbase.cache.CouchbaseCacheManager[] is auto-configured. It is possible to create additional caches on startup by setting the configprop:spring.cache.cache-names[] property and cache defaults can be configured by using spring.cache.couchbase.*properties. For instance, the following configuration createscache1andcache2` caches with an entry expiration of 10 minutes:

spring:
  cache:
    cache-names: "cache1,cache2"
    couchbase:
      expiration: "10m"

If you need more control over the configuration, consider registering a org.springframework.boot.autoconfigure.cache.CouchbaseCacheManagerBuilderCustomizer[] bean. The following example shows a customizer that configures a specific entry expiration for cache1andcache2`:

include-code::MyCouchbaseCacheManagerConfiguration[]

Redis

If Redis is available and configured, a org.springframework.data.redis.cache.RedisCacheManager[] is auto-configured. It is possible to create additional caches on startup by setting the configprop:spring.cache.cache-names[] property and cache defaults can be configured by using spring.cache.redis.*properties. For instance, the following configuration createscache1andcache2` caches with a time to live of 10 minutes:

spring:
  cache:
    cache-names: "cache1,cache2"
    redis:
      time-to-live: "10m"

Note

By default, a key prefix is added so that, if two separate caches use the same key, Redis does not have overlapping keys and cannot return invalid values. We strongly recommend keeping this setting enabled if you create your own `org.springframework.data.redis.cache.RedisCacheManager[].

Tip

You can take full control of the default configuration by adding a org.springframework.data.redis.cache.RedisCacheConfiguration[] org.springframework.context.annotation.Bean`[format=annotation] of your own. This can be useful if you need to customize the default serialization strategy.

If you need more control over the configuration, consider registering a org.springframework.boot.autoconfigure.cache.RedisCacheManagerBuilderCustomizer[] bean. The following example shows a customizer that configures a specific time to live for cache1andcache2`:

include-code::MyRedisCacheManagerConfiguration[]

Caffeine

Caffeine is a Java 8 rewrite of Guava’s cache that supersedes support for Guava. If Caffeine is present, a org.springframework.cache.caffeine.CaffeineCacheManager[] (provided by the spring-boot-starter-cache` starter) is auto-configured. Caches can be created on startup by setting the configprop:spring.cache.cache-names[] property and can be customized by one of the following (in the indicated order):

1. A cache spec defined by spring.cache.caffeine.spec

2. A `com.github.benmanes.caffeine.cache.CaffeineSpec[] bean is defined

3. A `com.github.benmanes.caffeine.cache.Caffeine[] bean is defined

For instance, the following configuration creates cache1 and cache2 caches with a maximum size of 500 and a time to live of 10 minutes

spring:
  cache:
    cache-names: "cache1,cache2"
    caffeine:
      spec: "maximumSize=500,expireAfterAccess=600s"

If a com.github.benmanes.caffeine.cache.CacheLoader[] bean is defined, it is automatically associated to the org.springframework.cache.caffeine.CaffeineCacheManager[]. Since the com.github.benmanes.caffeine.cache.CacheLoader[] is going to be associated with *all* caches managed by the cache manager, it must be defined as CacheLoader<Object, Object>`. The auto-configuration ignores any other generic type.

Cache2k

Cache2k is an in-memory cache. If the Cache2k spring integration is present, a SpringCache2kCacheManager is auto-configured.

Caches can be created on startup by setting the configprop:spring.cache.cache-names[] property. Cache defaults can be customized using a `org.springframework.boot.autoconfigure.cache.Cache2kBuilderCustomizer[] bean. The following example shows a customizer that configures the capacity of the cache to 200 entries, with an expiration of 5 minutes:

include-code::MyCache2kDefaultsConfiguration[]

Simple

If none of the other providers can be found, a simple implementation using a java.util.concurrent.ConcurrentHashMap[] as the cache store is configured. This is the default if no caching library is present in your application. By default, caches are created as needed, but you can restrict the list of available caches by setting the cache-namesproperty. For instance, if you want onlycache1andcache2caches, set thecache-names` property as follows:

spring:
  cache:
    cache-names: "cache1,cache2"

If you do so and your application uses a cache not listed, then it fails at runtime when the cache is needed, but not on startup. This is similar to the way the "real" cache providers behave if you use an undeclared cache.

None

When org.springframework.cache.annotation.EnableCaching[format=annotation] is present in your configuration, a suitable cache configuration is expected as well. If you have a custom org.springframework.cache.CacheManager, consider defining it in a separate org.springframework.context.annotation.Configuration[format=annotation] class so that you can override it if necessary. None uses a no-op implementation that is useful in tests, and slice tests use that by default via org.springframework.boot.test.autoconfigure.core.AutoConfigureCache[format=annotation].

If you need to use a no-op cache rather than the auto-configured cache manager in a certain environment, set the cache type to none, as shown in the following example:

spring:
  cache:
    type: "none"