reactor.util.context

Interface ContextView

All Known Subinterfaces:

Context

public interface ContextView

A read-only view of a collection of key/value pairs that is propagated between components such as operators via the context protocol. Contexts are ideal to transport orthogonal information such as tracing or security tokens.

Context is an immutable variant of the same key/value pairs structure which exposes a write API that returns new instances on each write.

Since:

3.4.0

Author:

Simon Baslé

Method Summary

Modifier and Type	Method and Description
default void	forEach(java.util.function.BiConsumer<java.lang.Object,java.lang.Object> action) Perform the given action for each entry in this ContextView.
default <T> T	get(java.lang.Class<T> key) Resolve a value given a type key within the Context.
<T> T	get(java.lang.Object key) Resolve a value given a key that exists within the Context, or throw a NoSuchElementException if the key is not present.
default <T> T	getOrDefault(java.lang.Object key, T defaultValue) Resolve a value given a key within the Context.
default <T> java.util.Optional<T>	getOrEmpty(java.lang.Object key) Resolve a value given a key within the Context.
boolean	hasKey(java.lang.Object key) Return true if a particular key resolves to a value within the Context.
default boolean	isEmpty() Return true if the Context is empty.
int	size() Return the size of this Context, the number of immutable key/value pairs stored inside it.
java.util.stream.Stream<java.util.Map.Entry<java.lang.Object,java.lang.Object>>	stream() Stream key/value pairs from this Context

Method Detail

get

<T> T get(java.lang.Object key)

Resolve a value given a key that exists within the Context, or throw a NoSuchElementException if the key is not present.

Type Parameters:

T - an unchecked casted generic for fluent typing convenience

Parameters:

key - a lookup key to resolve the value within the context

Returns:

the value resolved for this key (throws if key not found)

Throws:

java.util.NoSuchElementException - when the given key is not present

See Also:

getOrDefault(Object, Object), getOrEmpty(Object), hasKey(Object)

get

default <T> T get(java.lang.Class<T> key)

Resolve a value given a type key within the Context.

Type Parameters:

T - an unchecked casted generic for fluent typing convenience

Parameters:

key - a type key to resolve the value within the context

Returns:

the value resolved for this type key (throws if key not found)

Throws:

java.util.NoSuchElementException - when the given type key is not present

See Also:

getOrDefault(Object, Object), getOrEmpty(Object)

getOrDefault

@Nullable
default <T> T getOrDefault(java.lang.Object key,
                                     @Nullable
                                     T defaultValue)

Resolve a value given a key within the Context. If unresolved return the passed default value.

Parameters:

key - a lookup key to resolve the value within the context

defaultValue - a fallback value if key doesn't resolve

Returns:

the value resolved for this key, or the given default if not present

getOrEmpty

default <T> java.util.Optional<T> getOrEmpty(java.lang.Object key)

Resolve a value given a key within the Context.

Parameters:

key - a lookup key to resolve the value within the context

Returns:

an Optional of the value for that key.

hasKey

boolean hasKey(java.lang.Object key)

Return true if a particular key resolves to a value within the Context.

Parameters:

key - a lookup key to test for

Returns:

true if this context contains the given key

isEmpty

default boolean isEmpty()

Return true if the Context is empty.

Returns:

true if the Context is empty.

size

int size()

Return the size of this Context, the number of immutable key/value pairs stored inside it.

Returns:

the size of the Context

stream

java.util.stream.Stream<java.util.Map.Entry<java.lang.Object,java.lang.Object>> stream()

Stream key/value pairs from this Context

Returns:

a Stream of key/value pairs held by this context

forEach

default void forEach(java.util.function.BiConsumer<java.lang.Object,java.lang.Object> action)

Perform the given action for each entry in this ContextView. If the action throws an exception, it is immediately propagated to the caller and the remaining items will not be processed.

Parameters:

action - The action to be performed for each entry

Throws:

java.lang.NullPointerException - if the specified action is null