org.springframework.cache.support

类 AbstractValueAdaptingCache

java.lang.Object

org.springframework.cache.support.AbstractValueAdaptingCache

所有已实现的接口:

Cache

直接已知子类:

CaffeineCache

public abstract class AbstractValueAdaptingCache
extends Object
implements Cache

Common base class for Cache implementations that need to adapt null values (and potentially other such special values) before passing them on to the underlying store.

Transparently replaces given null user values with an internal NullValue.INSTANCE, if configured to support null values (as indicated by isAllowNullValues().

从以下版本开始:

4.2.2

作者:

Juergen Hoeller

嵌套类概要

从接口继承的嵌套类/接口 org.springframework.cache.Cache

Cache.ValueRetrievalException, Cache.ValueWrapper

构造器概要

构造器

限定符	构造器和说明
protected	AbstractValueAdaptingCache(boolean allowNullValues) Create an AbstractValueAdaptingCache with the given setting.

方法概要

限定符和类型	方法和说明
protected Object	fromStoreValue(Object storeValue) Convert the given value from the internal store to a user value returned from the get method (adapting null).
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.
boolean	isAllowNullValues() Return whether null values are allowed in this cache.
protected abstract Object	lookup(Object key) Perform an actual lookup in the underlying store.
protected Object	toStoreValue(Object userValue) Convert the given user value, as passed into the put method, to a value in the internal store (adapting null).
protected Cache.ValueWrapper	toValueWrapper(Object storeValue) Wrap the given store value with a SimpleValueWrapper, also going through fromStoreValue(java.lang.Object) conversion.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

从接口继承的方法 org.springframework.cache.Cache

clear, evict, evictIfPresent, get, getName, getNativeCache, invalidate, put, putIfAbsent

构造器详细资料

AbstractValueAdaptingCache

protected AbstractValueAdaptingCache(boolean allowNullValues)

Create an AbstractValueAdaptingCache with the given setting.

参数:

allowNullValues - whether to allow for null values

方法详细资料

isAllowNullValues

public final boolean isAllowNullValues()

Return whether null values are allowed in this cache.

get

@Nullable
public Cache.ValueWrapper get(Object key)

从接口复制的说明: Cache

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.

指定者:

get 在接口中 Cache

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 cached null value. A straight null being returned means that the cache contains no mapping for this key.

另请参阅:

Cache.get(Object, Class), Cache.get(Object, Callable)

get

@Nullable
public <T> T get(Object key,
                           @Nullable
                           Class<T> type)

从接口复制的说明: Cache

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 cached null value and no cache entry found at all. Use the standard Cache.get(Object) variant for that purpose instead.

指定者:

get 在接口中 Cache

参数:

key - the key whose associated value is to be returned

type - 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)

返回:

the value to which this cache maps the specified key (which may be null itself), or also null if the cache contains no mapping for this key

另请参阅:

Cache.get(Object)

lookup

@Nullable
protected abstract Object lookup(Object key)

Perform an actual lookup in the underlying store.

参数:

key - the key whose associated value is to be returned

返回:

the raw store value for the key, or null if none

fromStoreValue

@Nullable
protected Object fromStoreValue(@Nullable
                                          Object storeValue)

Convert the given value from the internal store to a user value returned from the get method (adapting null).

参数:

storeValue - the store value

返回:

the value to return to the user

toStoreValue

protected Object toStoreValue(@Nullable
                              Object userValue)

Convert the given user value, as passed into the put method, to a value in the internal store (adapting null).

参数:

userValue - the given user value

返回:

the value to store

toValueWrapper

@Nullable
protected Cache.ValueWrapper toValueWrapper(@Nullable
                                                      Object storeValue)

Wrap the given store value with a SimpleValueWrapper, also going through fromStoreValue(java.lang.Object) conversion. Useful for get(Object) and Cache.putIfAbsent(Object, Object) implementations.

参数:

storeValue - the original value

返回:

the wrapped value