ej.service

Interface ServiceLoader

All Known Subinterfaces:

ServiceRegistry, SharedServiceRegistry

All Known Implementing Classes:

CompositeServiceLoader, DependencyInjectionServiceLoader, FilePropertiesServiceLoader, MetaInfServiceLoader, SimpleServiceLoader, SimpleServiceRegistry, SystemPropertiesServiceLoader

public interface ServiceLoader

A simple service loading facility.

A service is usually defined by an interface (but that may be a class). The service loader associates a service with an instance of this service. This instance may be retrieved in different ways:

• dependency injection: the implementation of the service is described in a configuration file (properties file for example) and this implementation is instantiated on demand. Once the instance is created, it is kept for ever.
• service registration: the instance is explicitly registered at runtime by a service provider.

Method Summary

Modifier and Type	Method and Description
<T> T	getService(Class<T> service) Gets the instance of the given service.

Method Detail

getService

@Nullable
<T> T getService(Class<T> service)

Gets the instance of the given service.

If there is already an instance in cache, it is returned otherwise a new one is created.

May return null if the service is not defined.

Type Parameters:

T - the service type.

Parameters:

service - the service.

Returns:

the instance of the given service.

Throws:

ServiceLoadingException - if an error occurs while instantiating the service instance.

SecurityException - if a security manager exists and does not allow the caller to retrieve the given service instance.