接口 Cache
- 所有已知实现类:
AbstractValueAdaptingCache
,CaffeineCache
,ConcurrentMapCache
,EhCacheCache
,GuavaCache
,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
).- 从以下版本开始:
- 3.1
- 作者:
- Costin Leau, Juergen Hoeller, Stephane Nicoll
嵌套类概要
嵌套类 修饰符和类型 接口 说明 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.
方法概要
所有方法 实例方法 抽象方法 修饰符和类型 方法 说明 void
clear()
Remove all mappings from the cache.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, 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.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.
方法详细资料
getNativeCache
Object getNativeCache()
Return the underlying native cache provider.
get
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
.- 参数:
key
- the key whose associated value is to be returned- 返回:
- 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. - 另请参阅:
get(Object, Class)
get
<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.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.- 参数:
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)- 返回:
- 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 - 抛出:
IllegalStateException
- if a cache entry has been found but failed to match the specified type- 从以下版本开始:
- 4.0
- 另请参阅:
get(Object)
get
<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
- 参数:
key
- the key whose associated value is to be returned- 返回:
- the value to which this cache maps the specified key
- 抛出:
Cache.ValueRetrievalException
- if thevalueLoader
throws an exception- 从以下版本开始:
- 4.3
put
void put(Object key, 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.
- 参数:
key
- the key with which the specified value is to be associatedvalue
- the value to be associated with the specified key
putIfAbsent
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.This is equivalent to:
except that the action is performed atomically. While all out-of-the-boxObject existingValue = cache.get(key); if (existingValue == null) { cache.put(key, value); return null; } else { 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.- 参数:
key
- the key with which the specified value is to be associatedvalue
- the value to be associated with the specified key- 返回:
- 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. - 从以下版本开始:
- 4.1
evict
void evict(Object key)
Evict the mapping for this key from this cache if it is present.- 参数:
key
- the key whose mapping is to be removed from the cache
clear
void clear()
Remove all mappings from the cache.