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 return null).
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 be null itself) will
be returned in a Cache.ValueWrapper.
key - the key whose associated value is to be returned
the value to which this cache maps the specified key,
contained within a Cache.ValueWrapper which may also hold
a cached null value. A straight null being
returned means that the cache contains no mapping for this key.
<T> T get(java.lang.Object key,
Return the value to which this cache maps the specified key, obtaining
that value from valueLoader 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.
except that the action is performed atomically. While all out-of-the-box
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.
key - the key with which the specified value is to be associated
value - the value to be associated with the specified key
the value to which this cache maps the specified key (which may be
null itself), or also null if the cache did not contain any
mapping for that key prior to this call. Returning null is therefore
an indicator that the given value has been associated with the key.
void evict(java.lang.Object key)
Evict the mapping for this key from this cache if it is present.
key - the key whose mapping is to be removed from the cache