public interface Cache
null
).Modifier and Type | Interface and Description |
---|---|
static class |
Cache.ValueRetrievalException
Wrapper exception to be thrown from
get(Object, Callable)
in case of the value loader callback failing with an exception. |
static interface |
Cache.ValueWrapper
A (wrapper) object representing a cache value.
|
Modifier and Type | Method and 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.
|
Cache.ValueWrapper |
get(Object key)
Return the value to which this cache maps the specified key.
|
<T> T |
get(Object key,
Callable<T> valueLoader)
Return the value to which this cache maps the specified key, obtaining
that value from
valueLoader if necessary. |
<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.
|
String |
getName()
Return the cache name.
|
Object |
getNativeCache()
Return the underlying native cache provider.
|
void |
put(Object key,
Object value)
Associate the specified value with the specified key in this cache.
|
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.
|
String getName()
Object getNativeCache()
@Nullable Cache.ValueWrapper get(Object 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 returnedCache.ValueWrapper
which may also hold
a cached null
value. A straight null
being
returned means that the cache contains no mapping for this key.get(Object, Class)
,
get(Object, Callable)
@Nullable <T> T get(Object key, @Nullable Class<T> type)
Note: This variant of get
does not allow for differentiating
between a cached null
value and no cache entry found at all.
Use the standard get(Object)
variant for that purpose instead.
key
- the key whose associated value is to be returnedtype
- the required type of the returned value (may be
null
to bypass a type check; in case of a null
value found in the cache, the specified type is irrelevant)null
itself), or also null
if
the cache contains no mapping for this keyIllegalStateException
- if a cache entry has been found
but failed to match the specified typeget(Object)
@Nullable <T> T get(Object key, Callable<T> valueLoader)
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.
If the valueLoader
throws an exception, it is wrapped in
a Cache.ValueRetrievalException
key
- the key whose associated value is to be returnedCache.ValueRetrievalException
- if the valueLoader
throws an exceptionget(Object)
void put(Object key, @Nullable Object value)
If the cache previously contained a mapping for this key, the old value is replaced by the specified value.
key
- the key with which the specified value is to be associatedvalue
- the value to be associated with the specified key@Nullable Cache.ValueWrapper putIfAbsent(Object key, @Nullable Object value)
This is equivalent to:
ValueWrapper existingValue = cache.get(key);
if (existingValue == null) {
cache.put(key, value);
}
return existingValue;
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 associatedvalue
- the value to be associated with the specified keynull
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.put(Object, Object)
void evict(Object key)
key
- the key whose mapping is to be removed from the cachevoid clear()