Cacheable (Spring Framework 4.3.13.RELEASE API)

```
@Target(value={METHOD,TYPE})
 @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 stored in the associated cache. Note that Java8's Optional return types are automatically handled and its content is stored in the cache if present.
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
`java.lang.String`	`cacheManager` The bean name of the custom `CacheManager` to use to create a default `CacheResolver` if none is set already.
`java.lang.String[]`	`cacheNames` Names of the caches in which method invocation results are stored.
`java.lang.String`	`cacheResolver` The bean name of the custom `CacheResolver` to use.
`java.lang.String`	`condition` Spring Expression Language (SpEL) expression used for making the method caching conditional.
`java.lang.String`	`key` Spring Expression Language (SpEL) expression for computing the key dynamically.
`java.lang.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.
`java.lang.String`	`unless` Spring Expression Language (SpEL) expression used to veto method caching.
`java.lang.String[]`	`value` Alias for `cacheNames()`.

- Element Detail
  - value
```
@AliasFor(value="cacheNames")
public abstract java.lang.String[] value
```
    Alias for cacheNames().
    
    Default:
    
    {}
- - cacheNames
```
@AliasFor(value="value")
public abstract java.lang.String[] cacheNames
```
    Names of the caches in which method invocation results are stored.
    Names may be used to determine the target cache (or caches), matching the qualifier value or bean name of a specific bean definition.
    
    Since:
    
    4.2
    
    See Also:
    
    value(), CacheConfig.cacheNames()
    
    Default:
    
    {}
- - key
```
public abstract java.lang.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 java.lang.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 java.lang.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 java.lang.String cacheResolver
```
    The bean name of the custom CacheResolver to use.
    
    See Also:
    
    CacheConfig.cacheResolver()
    
    Default:
    
    ""
- - condition
```
public abstract java.lang.String condition
```
    Spring Expression Language (SpEL) expression used for making the method caching conditional.
    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 java.lang.String unless
```
    Spring Expression Language (SpEL) expression used to veto method caching.
    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 actual cache provider that you are using may not 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

Annotation Type Cacheable

Optional Element Summary

Element Detail

value

cacheNames

key

keyGenerator

cacheManager

cacheResolver

condition

unless

sync