Interface Cache
- All Known Implementing Classes:
AbstractValueAdaptingCache
,CaffeineCache
,ConcurrentMapCache
,EhCacheCache
,JCacheCache
,NoOpCache
,TransactionAwareCacheDecorator
public interface Cache
Interface that defines common cache operations. Note: Due to the generic use of caching, it is recommended that implementations allow storage of null values (for example to cache methods that returnnull
).- Since:
- 3.1
- Author:
- Costin Leau, Juergen Hoeller, Stephane Nicoll
Nested Class Summary
Nested Classes Modifier and Type Interface Description static class
Cache.ValueRetrievalException
Wrapper exception to be thrown fromget(Object, Callable)
in case of the value loader callback failing with an exception.static interface
Cache.ValueWrapper
A (wrapper) object representing a cache value.
Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description void
clear()
Clear the cache through removing all mappings.void
evict(Object key)
Evict the mapping for this key from this cache if it is present.default boolean
evictIfPresent(Object key)
Evict the mapping for this key from this cache if it is present, expecting the key to be immediately invisible for subsequent lookups.Cache.ValueWrapper
get(Object key)
Return the value to which this cache maps the specified key.<T> T
get(Object key, Class<T> type)
Return the value to which this cache maps the specified key, generically specifying a type that return value will be cast to.<T> T
get(Object key, Callable<T> valueLoader)
Return the value to which this cache maps the specified key, obtaining that value fromvalueLoader
if necessary.String
getName()
Return the cache name.Object
getNativeCache()
Return the underlying native cache provider.default boolean
invalidate()
Invalidate the cache through removing all mappings, expecting all entries to be immediately invisible for subsequent lookups.void
put(Object key, Object value)
Associate the specified value with the specified key in this cache.default Cache.ValueWrapper
putIfAbsent(Object key, Object value)
Atomically associate the specified value with the specified key in this cache if it is not set already.
Method Detail
getNativeCache
Object getNativeCache()
Return the underlying native cache provider.
get
@Nullable Cache.ValueWrapper get(Object key)
Return the value to which this cache maps the specified key.Returns
null
if the cache contains no mapping for this key; otherwise, the cached value (which may benull
itself) will be returned in aCache.ValueWrapper
.- Parameters:
key
- the key whose associated value is to be returned- Returns:
- the value to which this cache maps the specified key, contained within a
Cache.ValueWrapper
which may also hold a cachednull
value. A straightnull
being returned means that the cache contains no mapping for this key. - See Also:
get(Object, Class)
,get(Object, Callable)
get
@Nullable <T> T get(Object key, @Nullable Class<T> type)
Return the value to which this cache maps the specified key, generically specifying a type that return value will be cast to.Note: This variant of
get
does not allow for differentiating between a cachednull
value and no cache entry found at all. Use the standardget(Object)
variant for that purpose instead.- Parameters:
key
- the key whose associated value is to be returnedtype
- the required type of the returned value (may benull
to bypass a type check; in case of anull
value found in the cache, the specified type is irrelevant)- Returns:
- the value to which this cache maps the specified key (which may be
null
itself), or alsonull
if the cache contains no mapping for this key - Throws:
IllegalStateException
- if a cache entry has been found but failed to match the specified type- Since:
- 4.0
- See Also:
get(Object)
get
@Nullable <T> T get(Object key, Callable<T> valueLoader)
Return the value to which this cache maps the specified key, obtaining that value fromvalueLoader
if necessary. This method provides a simple substitute for the conventional "if cached, return; otherwise create, cache and return" pattern.If possible, implementations should ensure that the loading operation is synchronized so that the specified
valueLoader
is only called once in case of concurrent access on the same key.If the
valueLoader
throws an exception, it is wrapped in aCache.ValueRetrievalException
- Parameters:
key
- the key whose associated value is to be returned- Returns:
- the value to which this cache maps the specified key
- Throws:
Cache.ValueRetrievalException
- if thevalueLoader
throws an exception- Since:
- 4.3
- See Also:
get(Object)
put
void put(Object key, @Nullable Object value)
Associate the specified value with the specified key in this cache.If the cache previously contained a mapping for this key, the old value is replaced by the specified value.
Actual registration may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly not seeing the entry yet. This may for example be the case with transactional cache decorators. Use
putIfAbsent(java.lang.Object, java.lang.Object)
for guaranteed immediate registration.- Parameters:
key
- the key with which the specified value is to be associatedvalue
- the value to be associated with the specified key- See Also:
putIfAbsent(Object, Object)
putIfAbsent
@Nullable default Cache.ValueWrapper putIfAbsent(Object key, @Nullable Object value)
Atomically associate the specified value with the specified key in this cache if it is not set already.This is equivalent to:
except that the action is performed atomically. While all out-of-the-boxValueWrapper existingValue = cache.get(key); if (existingValue == null) { cache.put(key, value); } return existingValue;
CacheManager
implementations are able to perform the put atomically, the operation may also be implemented in two steps, e.g. with a check for presence and a subsequent put, in a non-atomic way. Check the documentation of the native cache implementation that you are using for more details.The default implementation delegates to
get(Object)
andput(Object, Object)
along the lines of the code snippet above.- Parameters:
key
- the key with which the specified value is to be associatedvalue
- the value to be associated with the specified key- Returns:
- the value to which this cache maps the specified key (which may be
null
itself), or alsonull
if the cache did not contain any mapping for that key prior to this call. Returningnull
is therefore an indicator that the givenvalue
has been associated with the key. - Since:
- 4.1
- See Also:
put(Object, Object)
evict
void evict(Object key)
Evict the mapping for this key from this cache if it is present.Actual eviction may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly still seeing the entry. This may for example be the case with transactional cache decorators. Use
evictIfPresent(java.lang.Object)
for guaranteed immediate removal.- Parameters:
key
- the key whose mapping is to be removed from the cache- See Also:
evictIfPresent(Object)
evictIfPresent
default boolean evictIfPresent(Object key)
Evict the mapping for this key from this cache if it is present, expecting the key to be immediately invisible for subsequent lookups.The default implementation delegates to
evict(Object)
, returningfalse
for not-determined prior presence of the key. Cache providers and in particular cache decorators are encouraged to perform immediate eviction if possible (e.g. in case of generally deferred cache operations within a transaction) and to reliably determine prior presence of the given key.- Parameters:
key
- the key whose mapping is to be removed from the cache- Returns:
true
if the cache was known to have a mapping for this key before,false
if it did not (or if prior presence could not be determined)- Since:
- 5.2
- See Also:
evict(Object)
clear
void clear()
Clear the cache through removing all mappings.Actual clearing may be performed in an asynchronous or deferred fashion, with subsequent lookups possibly still seeing the entries. This may for example be the case with transactional cache decorators. Use
invalidate()
for guaranteed immediate removal of entries.- See Also:
invalidate()
invalidate
default boolean invalidate()
Invalidate the cache through removing all mappings, expecting all entries to be immediately invisible for subsequent lookups.- Returns:
true
if the cache was known to have mappings before,false
if it did not (or if prior presence of entries could not be determined)- Since:
- 5.2
- See Also:
clear()