org.springframework.cache.annotation

Annotation Type Cacheable

@Target(value={TYPE,METHOD})
 @Retention(value=RUNTIME)
 @Inherited
 @Documented
public @interface Cacheable

Annotation indicating that the result of invoking a method (or all methods in a class) can be cached.

Each time an advised method is invoked, caching behavior will be applied, checking whether the method has been already invoked for the given arguments. A sensible default simply uses the method parameters to compute the key, but a SpEL expression can be provided via the key() attribute, or a custom KeyGenerator implementation can replace the default one (see keyGenerator()).

If no value is found in the cache for the computed key, the target method will be invoked and the returned value will be stored in the associated cache. Note that Optional return types are unwrapped automatically. If an Optional value is present, it will be stored in the associated cache. If an Optional value is not present, null will be stored in the associated cache.

This annotation may be used as a meta-annotation to create custom composed annotations with attribute overrides.

Since:

3.1

Author:

Costin Leau, Phillip Webb, Stephane Nicoll, Sam Brannen

See Also:

CacheConfig

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String	cacheManager The bean name of the custom CacheManager to use to create a default CacheResolver if none is set already.
String[]	cacheNames Names of the caches in which method invocation results are stored.
String	cacheResolver The bean name of the custom CacheResolver to use.
String	condition Spring Expression Language (SpEL) expression used for making the method caching conditional.
String	key Spring Expression Language (SpEL) expression for computing the key dynamically.
String	keyGenerator The bean name of the custom KeyGenerator to use.
boolean	sync Synchronize the invocation of the underlying method if several threads are attempting to load a value for the same key.
String	unless Spring Expression Language (SpEL) expression used to veto method caching.
String[]	value Alias for cacheNames().

Element Detail

value

@AliasFor(value="cacheNames")
public abstract String[] value

Alias for cacheNames().

Default:

{}

cacheNames

@AliasFor(value="value")
public abstract String[] cacheNames

Names of the caches in which method invocation results are stored.

Names may be used to determine the target cache(s), to be resolved via the configured cacheResolver() which typically delegates to CacheManager.getCache(java.lang.String).

This will usually be a single cache name. If multiple names are specified, they will be consulted for a cache hit in the order of definition, and they will all receive a put/evict request for the same newly cached value.

Since:

4.2

See Also:

value(), CacheConfig.cacheNames()

Default:

{}

key

public abstract String key

Spring Expression Language (SpEL) expression for computing the key dynamically.

Default is "", meaning all method parameters are considered as a key, unless a custom keyGenerator() has been configured.

The SpEL expression evaluates against a dedicated context that provides the following meta-data:

• #root.method, #root.target, and #root.caches for references to the method, target object, and affected cache(s) respectively.
• Shortcuts for the method name (#root.methodName) and target class (#root.targetClass) are also available.
• Method arguments can be accessed by index. For instance the second argument can be accessed via #root.args[1], #p1 or #a1. Arguments can also be accessed by name if that information is available.

Default:

""

keyGenerator

public abstract String keyGenerator

The bean name of the custom KeyGenerator to use.

Mutually exclusive with the key() attribute.

See Also:

CacheConfig.keyGenerator()

Default:

""

cacheManager

public abstract String cacheManager

The bean name of the custom CacheManager to use to create a default CacheResolver if none is set already.

Mutually exclusive with the cacheResolver() attribute.

See Also:

SimpleCacheResolver, CacheConfig.cacheManager()

Default:

""

cacheResolver

public abstract String cacheResolver

The bean name of the custom CacheResolver to use.

See Also:

CacheConfig.cacheResolver()

Default:

""

condition

public abstract String condition

Spring Expression Language (SpEL) expression used for making the method caching conditional. Cache the result if the condition evaluates to true.

Default is "", meaning the method result is always cached.

The SpEL expression evaluates against a dedicated context that provides the following meta-data:

• #root.method, #root.target, and #root.caches for references to the method, target object, and affected cache(s) respectively.
• Shortcuts for the method name (#root.methodName) and target class (#root.targetClass) are also available.
• Method arguments can be accessed by index. For instance the second argument can be accessed via #root.args[1], #p1 or #a1. Arguments can also be accessed by name if that information is available.

Default:

""

unless

public abstract String unless

Spring Expression Language (SpEL) expression used to veto method caching. Veto caching the result if the condition evaluates to true.

Unlike condition(), this expression is evaluated after the method has been called and can therefore refer to the result.

Default is "", meaning that caching is never vetoed.

The SpEL expression evaluates against a dedicated context that provides the following meta-data:

• #result for a reference to the result of the method invocation. For supported wrappers such as Optional, #result refers to the actual object, not the wrapper
• #root.method, #root.target, and #root.caches for references to the method, target object, and affected cache(s) respectively.
• Shortcuts for the method name (#root.methodName) and target class (#root.targetClass) are also available.
• Method arguments can be accessed by index. For instance the second argument can be accessed via #root.args[1], #p1 or #a1. Arguments can also be accessed by name if that information is available.

Since:

3.2

Default:

""

sync

public abstract boolean sync

Synchronize the invocation of the underlying method if several threads are attempting to load a value for the same key. The synchronization leads to a couple of limitations:

1. unless() is not supported
2. Only one cache may be specified
3. No other cache-related operation can be combined

This is effectively a hint and the chosen cache provider might not actually support it in a synchronized fashion. Check your provider documentation for more details on the actual semantics.

Since:

4.3

See Also:

Cache.get(Object, Callable)

Default:

false