ej.components.dependencyinjection

Class AbstractServiceLoader

java.lang.Object

ej.components.dependencyinjection.AbstractServiceLoader

All Implemented Interfaces:

ServiceLoader, ServiceProvider

Direct Known Subclasses:

FilePropertiesServiceLoader, MetaInfServiceLoader, SystemPropertiesServiceLoader

public abstract class AbstractServiceLoader
extends Object
implements ServiceLoader

Abstract service loader that provides a default skeleton of service loader.

Subclasses need to provide the implementation class name matching the requested services. The implementation is then instantiated using Class.forName(String) and Class.newInstance(). The singletons are stored in a map.

Constructor Summary

Constructors

Constructor and Description
AbstractServiceLoader() Creates a new abstract service loader.

Method Summary

Modifier and Type	Method and Description
protected abstract String	getImplementationName(String key) Gets the implementation class name for the given key.
<T> T	getService(Class<T> service) Gets the instance of the given service.
<T> T	getService(Class<T> service, boolean singleton) Gets the registered implementation for the given service.
<T> T	getService(Class<T> service, Class<? extends T> defaultImplementation) Gets the registered implementation for the given service.
<T> T	getService(Class<T> service, Class<? extends T> defaultImplementation, boolean singleton) Gets the registered implementation for the given service.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractServiceLoader

public AbstractServiceLoader()

Creates a new abstract service loader.

Method Detail

getImplementationName

@Nullable
protected abstract String getImplementationName(String key)

Gets the implementation class name for the given key.

Parameters:

key - the service name.

Returns:

the implementation class name, or null if none.

getService

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

Description copied from interface: ServiceLoader

Gets the instance of the given service.

Equivalent to calling ServiceLoader.getService(Class, boolean) passing @{code true} as @{code singleton}.

Specified by:

getService in interface ServiceLoader

Specified by:

getService in interface ServiceProvider

Type Parameters:

T - the service type.

Parameters:

service - the service.

Returns:

the instance of the given service.

getService

@Nullable
public <T> T getService(Class<T> service,
                                   boolean singleton)

Description copied from interface: ServiceLoader

Gets the registered implementation for the given service.

If a singleton is asked and if an instance of this service has already been created, this instance is returned. Otherwise, creates a new instance of the implementation type.

Specified by:

getService in interface ServiceLoader

Type Parameters:

T - the service type.

Parameters:

service - the service.

singleton - if true returns an already created instance if any, creates a new one otherwise.

Returns:

an instance of the given service or null if no implementation is available.

getService

public <T> T getService(Class<T> service,
                        Class<? extends T> defaultImplementation)

Description copied from interface: ServiceLoader

Gets the registered implementation for the given service. If there is no registered implementation, an instance of the default implementation is returned.

Specified by:

getService in interface ServiceLoader

Type Parameters:

T - the service type.

Parameters:

service - the service.

defaultImplementation - the default implementation to use.

Returns:

the instance of the given service.

getService

public <T> T getService(Class<T> service,
                        Class<? extends T> defaultImplementation,
                        boolean singleton)

Description copied from interface: ServiceLoader

Gets the registered implementation for the given service. If there is no registered implementation, an instance of the default implementation is returned.

If a singleton is asked and if an instance of this service has already been created, this instance is returned. Otherwise, creates a new instance of the implementation type.

Specified by:

getService in interface ServiceLoader

Type Parameters:

T - the service type.

Parameters:

service - the service.

defaultImplementation - the default implementation to use.

singleton - if true returns an already created instance if any, creates a new one otherwise.

Returns:

an instance of the given service.