类 AbstractValueAdaptingCache

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