com.vaadin.flow.di

Interface Instantiator

All Superinterfaces:

Serializable

All Known Implementing Classes:

DefaultInstantiator

public interface Instantiator
extends Serializable

Delegate for discovering, creating and managing instances of various types used by Flow. Dependency injection frameworks can provide an implementation that manages instances according to the conventions of that framework.

VaadinService will by default use ServiceLoader for finding an instantiator implementation. Deployment will fail if multiple candidates are returning true from init(VaadinService). If no candidate is found, DefaultInstantiator will be used. It is possible to override this mechanism by overriding VaadinService.createInstantiator().

Since:

1.0

Author:

Vaadin Ltd

Method Summary

Modifier and Type	Method and Description
default <T extends Component> T	createComponent(Class<T> componentClass) Creates an instance of a component by its componentClass.
default <T extends HasElement> T	createRouteTarget(Class<T> routeTargetType, NavigationEvent event) Creates an instance of a navigation target or router layout.
static Instantiator	get(UI ui) Gets the instantiator to use for the given UI.
default Stream<BootstrapListener>	getBootstrapListeners(Stream<BootstrapListener> serviceInitListeners) Processes the available bootstrap listeners.
default Stream<DependencyFilter>	getDependencyFilters(Stream<DependencyFilter> serviceInitFilters) Processes the available dependency filters.
default I18NProvider	getI18NProvider() Get the I18NProvider if one has been defined.
<T> T	getOrCreate(Class<T> type) Provides an instance of any given type, this is an abstraction that allows to make use of DI-frameworks from add-ons.
Stream<VaadinServiceInitListener>	getServiceInitListeners() Gets all service init listeners to use.
boolean	init(VaadinService service) Initializes this instantiator.

Method Detail

init

boolean init(VaadinService service)

Initializes this instantiator. This method is run only once and before running any other method. An implementation can opt-out from being used by returning false. It is recommended that all implementations provide a way for application developers to disable an implementation so that it can be present on the classpath without preventing the application from being deployed in cases when multiple candidates are available.

Parameters:

service - the Vaadin service for which this instance is initialized

Returns:

true if this instance should be considered as a candidate for usage for the provided service; false to opt-out from the selection process

getServiceInitListeners

Stream<VaadinServiceInitListener> getServiceInitListeners()

Gets all service init listeners to use. In addition to listeners defined in some way native to a specific instantiator, it is also recommended to support the default ServiceLoader convention. This can be done by including the items from DefaultInstantiator.getServiceInitListeners() in the returned stream.

Returns:

stream of service init listeners, not null

getBootstrapListeners

default Stream<BootstrapListener> getBootstrapListeners(Stream<BootstrapListener> serviceInitListeners)

Processes the available bootstrap listeners. This method can supplement the set of bootstrap listeners provided by VaadinServiceInitListener implementations.

The default implementation returns the original listeners without changes.

The order of the listeners inside the stream defines the order of the execution of those listeners by the VaadinService.modifyBootstrapPage(BootstrapPageResponse) method.

Parameters:

serviceInitListeners - a stream of bootstrap listeners provided by service init listeners, not null

Returns:

a stream of all bootstrap listeners to use, not null

getDependencyFilters

default Stream<DependencyFilter> getDependencyFilters(Stream<DependencyFilter> serviceInitFilters)

Processes the available dependency filters. This method can supplement the set of dependency filters provided by VaadinServiceInitListener implementations.

The default implementation returns the original handlers without changes.

The order of the filters inside the stream defines the order of the execution of those listeners by the UidlWriter.createUidl(UI, boolean) method.

Parameters:

serviceInitFilters - a stream of dependency filters provided by service init listeners, not null

Returns:

a stream of all dependency filters to use, not null

getOrCreate

<T> T getOrCreate(Class<T> type)

Provides an instance of any given type, this is an abstraction that allows to make use of DI-frameworks from add-ons.

How the object is created and whether it is being cached or not is up to the implementation.

Type Parameters:

T - the type of the instance to create

Parameters:

type - the instance type to create, not null

Returns:

an instance of the given type

createRouteTarget

default <T extends HasElement> T createRouteTarget(Class<T> routeTargetType,
                                                   NavigationEvent event)

Creates an instance of a navigation target or router layout. This method is not called in cases when a component instance is reused when navigating.

Type Parameters:

T - the route target type

Parameters:

routeTargetType - the instance type to create, not null

event - the navigation event for which the instance is created, not null

Returns:

the created instance, not null

createComponent

default <T extends Component> T createComponent(Class<T> componentClass)

Creates an instance of a component by its componentClass.

Type Parameters:

T - the component type

Parameters:

componentClass - the instance type to create, not null

Returns:

the created instance, not null

get

static Instantiator get(UI ui)

Gets the instantiator to use for the given UI.

Parameters:

ui - the attached UI for which to find an instantiator, not null

Returns:

the instantiator, not null

getI18NProvider

default I18NProvider getI18NProvider()

Get the I18NProvider if one has been defined.

Returns:

I18NProvier instance