Package javax.measure.spi

Class ServiceProvider

java.lang.Object

javax.measure.spi.ServiceProvider

public abstract class ServiceProvider
extends java.lang.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:

1.0, August 8, 2016

Field Summary

Fields

Modifier and Type	Field	Description
private static java.lang.Object	LOCK	Synchronization lock for searching or setting the service providers.
private static ServiceProvider[]	providers	All service providers found, sorted in preference order.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
static java.util.List<ServiceProvider>	available()	Returns the list of available service providers.
static ServiceProvider	current()	Returns the current ServiceProvider.
int	getPriority()	This method allows to define a priority for a registered ServiceProvider instance.
private static ServiceProvider[]	getProviders()	Gets all ServiceProvider.
abstract <Q extends Quantity<Q>> QuantityFactory<Q>	getQuantityFactory(java.lang.Class<Q> quantity)	Return a factory for this Quantity.
abstract SystemOfUnitsService	getSystemOfUnitsService()	Returns the service to obtain a SystemOfUnits, or null if none.
abstract UnitFormatService	getUnitFormatService()	Returns the service to obtain a UnitFormat, or null if none.
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

Field Detail

LOCK

private static final java.lang.Object LOCK

Synchronization lock for searching or setting the service providers.

providers

private static volatile ServiceProvider[] providers

All service providers found, sorted in preference order. Array content shall never been changed after initialization; if we want to change the array content, a new array shall be created.

Constructor Detail

ServiceProvider

protected ServiceProvider()

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

Method Detail

getPriority

public int getPriority()

This method 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.

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.

getUnitFormatService

public abstract UnitFormatService getUnitFormatService()

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

Returns:

the service to obtain a UnitFormat, or null.

getQuantityFactory

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

Return a factory for this Quantity.

Parameters:

quantity - the quantity

Returns:

the QuantityFactory

getProviders

private static ServiceProvider[] getProviders()

Gets all ServiceProvider. This method loads the provider when first needed.

available

public static java.util.List<ServiceProvider> available()

Returns the list of available service providers.

Returns:

all available service providers.

current

public static 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() .

Returns:

the ServiceProvider used.

Throws:

java.lang.IllegalStateException - if no ServiceProvider has been found.

See Also:

getPriority(), #setCurrent()

setCurrent

public static ServiceProvider setCurrent(ServiceProvider provider)

Replaces the current ServiceProvider.

Parameters:

provider - the new ServiceProvider

Returns:

the removed provider, or null.