Package javax.measure.spi

Class ServiceProvider

java.lang.Object

javax.measure.spi.ServiceProvider

public abstract class ServiceProvider
extends Object

Service Provider for Units of Measurement services.

All the methods in this class are safe to use by multiple concurrent threads.

Since:

1.0

Version:

2.2, November 16, 2020

Author:

Werner Keil, Martin Desruisseaux

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ServiceProvider()	Creates a new service provider.

Method Summary

Modifier and Type	Method	Description
static List<ServiceProvider>	available()	Returns the list of all service providers available for the current thread's context class loader.
static ServiceProvider	current()	Returns the current ServiceProvider.
abstract FormatService	getFormatService()	Returns the service to obtain UnitFormat and QuantityFormat or null if none.
int	getPriority()	Allows to define a priority for a registered ServiceProvider instance.
abstract <Q extends Quantity<Q>> QuantityFactory<Q>	getQuantityFactory(Class<Q> quantity)	Returns a factory for the given Quantity type.
abstract SystemOfUnitsService	getSystemOfUnitsService()	Returns the service to obtain a SystemOfUnits, or null if none.
static ServiceProvider	of(String name)	Returns the ServiceProvider with the specified name.
static ServiceProvider	setCurrent(ServiceProvider provider)	Replaces the current ServiceProvider.

Methods inherited from class java.lang.Object

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

Constructor Details

ServiceProvider

protected ServiceProvider()

Creates a new service provider. Only to be used by subclasses.

Method Details

getPriority

public int getPriority()

Allows to define a priority for a registered ServiceProvider instance. When multiple providers are registered in the system, the provider with the highest priority value is taken.

If the "javax.annotation.Priority" annotation (from JSR-250) or "jakarta.annotation.Priority" annotation (from Jakarta Annotations) is present on the ServiceProvider implementation class, then that annotation (first if both were present) is taken and this getPriority() method is ignored. Otherwise – if a Priority annotation is absent – this method is used as a fallback.

Returns:

the provider's priority (default is 0).

getSystemOfUnitsService

public abstract SystemOfUnitsService getSystemOfUnitsService()

Returns the service to obtain a SystemOfUnits, or null if none.

Returns:

the service to obtain a SystemOfUnits, or null.

getFormatService

public abstract FormatService getFormatService()

Returns the service to obtain UnitFormat and QuantityFormat or null if none.

Returns:

the service to obtain a UnitFormat and QuantityFormat, or null.

Since:

2.0

getQuantityFactory

public abstract <Q extends Quantity<Q>> QuantityFactory<Q> getQuantityFactory(Class<Q> quantity)

Returns a factory for the given Quantity type.

Type Parameters:

Q - the type of the Quantity instances created by the factory

Parameters:

quantity - the quantity type

Returns:

the QuantityFactory for the given type

available

public static final List<ServiceProvider> available()

Returns the list of all service providers available for the current thread's context class loader. The current service provider is always the first item in the returned list. Other service providers after the first item may depend on the caller thread (see service loader API note).

Returns:

all service providers available for the current thread's context class loader.

of

public static ServiceProvider of(String name)

Returns the ServiceProvider with the specified name. The given name must match the name of at least one service provider available in the current thread's context class loader. The service provider names are the values of "javax.inject.Named" annotations when present, or the value of Object.toString() method for providers without Named annotation.

Implementors are encouraged to provide an Named annotation or to override Object.toString() and use a unique enough name, e.g. the class name or other distinct attributes. Should multiple service providers nevertheless use the same name, the one with the highest priority wins.

Parameters:

name - the name of the service provider to return

Returns:

the ServiceProvider with the specified name

Throws:

IllegalArgumentException - if available service providers do not contain a provider with the specified name

NullPointerException - if name is null

Since:

2.0

See Also:

Object.toString()

current

public static final ServiceProvider current()

Returns the current ServiceProvider. If necessary the ServiceProvider will be lazily loaded.

If there are no providers available, an IllegalStateException is thrown. Otherwise the provider with the highest priority is used or the one explicitly designated via setCurrent(ServiceProvider).

Returns:

the ServiceProvider used.

Throws:

IllegalStateException - if no ServiceProvider has been found.

See Also:

getPriority(), setCurrent(ServiceProvider)

setCurrent

public static final ServiceProvider setCurrent(ServiceProvider provider)

Replaces the current ServiceProvider.

Parameters:

provider - the new ServiceProvider

Returns:

the replaced provider, or null.