io.micronaut.context

Interface BeanProvider<T>

Type Parameters:

T - The generic bean type

All Superinterfaces:

Iterable<T>

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface BeanProvider<T>
extends Iterable<T>

A BeanProvider is a richer replacement for the Provider interface that provides additional Micronaut specific methods to assist in programmatic bean creation and discovery.

Since:

2.4.0

Author:

James Kleeh, graemerocher

Method Summary

Modifier and Type	Method and Description
static <T1> Argument<BeanProvider<T1>>	argumentOf(Class<T1> type) Create an argument for the given type to aid with bean provider lookup.
default Optional<T>	find(Qualifier<T> qualifier) Finds a bean for the optionally specified qualifier.
T	get() The get method will materialize an instance of the bean if it is resolvable.
default T	get(Qualifier<T> qualifier)
default BeanDefinition<T>	getDefinition() Obtains a reference to the BeanDefinition if the bean is resolvable.
default void	ifPresent(Consumer<T> consumer) Executes the given logic if the bean is present.
default void	ifResolvable(Consumer<T> consumer) Executes the given logic if the bean is resolvable.
default boolean	isPresent() Determines if there is a bean that matches the required type and qualifiers.
default boolean	isResolvable() Is the bean resolvable using the get() or ifPresent(Consumer) methods.
default boolean	isUnique() Determines if more than one bean matches the specified type and qualifiers.
default Iterator<T>	iterator()
default T	orElse(T alternative) Allows selecting an alternative bean if the backing bean is not present.
default Stream<T>	stream() When called, provides back a Stream of the beans available in this provider.

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

get

@NonNull
T get()

The get method will materialize an instance of the bean if it is resolvable.

A bean is considered resolvable if it is both unique and present. See isUnique() and isPresent().

Note that if the bean is Singleton then multiple calls to this method will return the same instance.

Returns:

A fully-constructed and injected instance of T.

Throws:

BeanCreationException - If an error occurs during the creation of the bean

NoSuchBeanException - if the bean doesn't exist

NonUniqueBeanException - if more than one bean matching the current qualifier exists and cannot be resolved unambiguously

find

default Optional<T> find(@Nullable
                         Qualifier<T> qualifier)

Finds a bean for the optionally specified qualifier. Return empty if non-exists.

Parameters:

qualifier - The qualifier to use. Can be null which is equivalent to specifying the default qualifier.

Returns:

An optional of the bean.

Since:

3.2.0

getDefinition

@NonNull
default BeanDefinition<T> getDefinition()

Obtains a reference to the BeanDefinition if the bean is resolvable.

Returns:

The BeanDefinition

Throws:

NoSuchBeanException - if the bean doesn't exist

NonUniqueBeanException - if more than one bean matching the current qualifier exists and cannot be resolved unambiguously

UnsupportedOperationException - If the BeanProvider was obtained via other means other than dependency injection

Since:

3.2.0

get

@NonNull
default T get(@Nullable
                       Qualifier<T> qualifier)

Parameters:

qualifier - The qualifier to use, can be null.

Returns:

A fully-constructed and injected instance of T.

Throws:

BeanCreationException - If an error occurs during the creation of the bean

NoSuchBeanException - if the bean doesn't exist

NonUniqueBeanException - if more than one bean matching the current qualifier exists and cannot be resolved unambiguously

Since:

3.0.0

See Also:

get()

iterator

@NonNull
default Iterator<T> iterator()

Specified by:

iterator in interface Iterable<T>

stream

default Stream<T> stream()

When called, provides back a Stream of the beans available in this provider. If no beans are found, it returns an empty stream.

Returns:

a Stream representing the beans associated with this BeanProvider object

Since:

3.0.0

isUnique

default boolean isUnique()

Determines if more than one bean matches the specified type and qualifiers.

Returns:

true if only one bean matches.

Since:

3.0.0

isPresent

default boolean isPresent()

Determines if there is a bean that matches the required type and qualifiers.

Returns:

true if at least one bean matches.

Since:

3.0.0

isResolvable

default boolean isResolvable()

Is the bean resolvable using the get() or ifPresent(Consumer) methods.

A bean is said to be resolvable when it is both unique (see isUnique()) and present (see isPresent())

Returns:

True if the bean is resolvable

Since:

3.0.0

ifPresent

default void ifPresent(@NonNull
                       Consumer<T> consumer)

Executes the given logic if the bean is present. Executes get() to obtain the bean which may result in a NonUniqueBeanException if the bean is not unique.

Parameters:

consumer - the consumer

Throws:

NonUniqueBeanException - if the bean is not unique

Since:

3.0.0

See Also:

isPresent()

ifResolvable

default void ifResolvable(@NonNull
                          Consumer<T> consumer)

Executes the given logic if the bean is resolvable. See isResolvable().

Parameters:

consumer - the consumer

Since:

3.0.0

See Also:

isResolvable()

orElse

@Nullable
default T orElse(@Nullable
                           T alternative)

Allows selecting an alternative bean if the backing bean is not present.

Parameters:

alternative - The alternative, can be null

Returns:

The bean if present or else the supplied alternative

Since:

3.0.2

argumentOf

@NonNull
static <T1> Argument<BeanProvider<T1>> argumentOf(@NonNull
                                                           Class<T1> type)

Create an argument for the given type to aid with bean provider lookup.

Type Parameters:

T1 - The generic type

Parameters:

type - The type

Returns:

3.0.0