HK2 OSGi resource locator 3.0.0 · org.glassfish.hk2.osgiresourcelocator.ServiceLoader

Modifier and Type	Class and Description
public static interface	ServiceLoader.ProviderFactory<T>

Modifier and Type	Field and Description
private static ServiceLoader	_me Singleton

Access	Constructor and Description
pack-priv	ServiceLoader()

Method Summary

Modifier and Type	Method and Description
public static synchronized void	initialize(ServiceLoader singleton)
public static <T> Iterable<Class<T>>	Returns: classes corresponding to entries in META-INF/services file for the service class. lookupProviderClasses(Class<T> type of service requested serviceClass) It is not clear why one needs this method, but it is provided just in case one needs it.
pack-priv abstract <T> Iterable<Class<T>>	lookupProviderClasses1(Class<T> serviceType)
public static <T> Iterable<? extends T>	lookupProviderInstances(Class<T> serviceClass) Calling this method is equivalent to calling `lookupProviderInstances(Class, ProviderFactory)` with a null factory object.
public static <T> Iterable<? extends T>	lookupProviderInstances(Class<T> type of service requested serviceClass, ServiceLoader.ProviderFactory<T> ProviderFactory used to instantiate provider instance from a provider class. If null is supplied, it calls Class.newInstance to obtain a provider instance from provider class. factory) Returns: provider instances implementing the given service class.
pack-priv abstract <T> Iterable<? extends T>	lookupProviderInstances1(Class<T> serviceType, ServiceLoader.ProviderFactory<T> factory)
public static synchronized void	reset()

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

_me	back to summary
private static ServiceLoader _me Singleton

ServiceLoader	back to summary
pack-priv ServiceLoader()

Method Detail

initialize	back to summary
public static synchronized void initialize(ServiceLoader singleton)

lookupProviderClasses	back to summary
public static <T> Iterable<Class<T>> lookupProviderClasses(Class<T> serviceClass) It is not clear why one needs this method, but it is provided just in case one needs it. Returns classes found in META-INF/services/serviceClass.getName() in OSGi bundles. This method searches for such named resources in every OSGi bundle. For every resource found, it assumes that the file contains a class name. It loads the class name mentioned in that file using the bundle containing the resource. It does not check if the class mentioned in provider file actually implements/extends service class, because there are cases where it does not. JAXB is an example. JAXBContext provider file contains a class that's used as a factory class for JAXBContext. To handle such issues, yet not return classes that are not class loader compatible, this method will only return those classes which see the same service class as supplied in the parameter. Let's take an example. We have JAXB classes exported by JRE and there is a bundle A which contains JAXB API and implementation. The bundle B is wired to itself for JAXB classes. Assume a user supplied bundle B is wired to JRE's JAXB. When bundle B calls JAXBContext.createContext(JAXBContext.class), JRE's JAXBContext will use this API. The implementation will look for META-INF/services/JAXBContext files and find a file in JAXB bundle. Let's say that file contains com.acme.jaxb.JAXBContextFactory. com.acme.jaxb.ContextFactory does not implement JAXBContext.class. Instead, as per JAXB spec, it must provide some factory methods to create JAXBContext. If our implementation simply returns that class without doing any further tests, a nasty class cast exception is going to be resulted, because user's bundle B uses JAXB from JRE, which means JAXBContext.class is loaded by JRE, yet com.acme.jaxb.JAXBContextFactory uses JAXBContext from bundle A. To avoid such problem, we will try to load JAXBContext using class loader of com.acme.jaxb.JAXBContextFactory and see if that's same as supplied JAXBContext.class. If they are same, we return com.acme.jaxb.JAXBContextFactory, else we don't. In this example, we won't. Parameters serviceClass:Class<T> type of service requested Returns:Iterable<Class<T>> classes corresponding to entries in META-INF/services file for the service class.

lookupProviderClasses

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public static <T> Iterable<Class<T>> lookupProviderClasses(Class<T> serviceClass)

It is not clear why one needs this method, but it is provided just in case one needs it. Returns classes found in META-INF/services/serviceClass.getName() in OSGi bundles. This method searches for such named resources in every OSGi bundle. For every resource found, it assumes that the file contains a class name. It loads the class name mentioned in that file using the bundle containing the resource. It does not check if the class mentioned in provider file actually implements/extends service class, because there are cases where it does not. JAXB is an example. JAXBContext provider file contains a class that's used as a factory class for JAXBContext. To handle such issues, yet not return classes that are not class loader compatible, this method will only return those classes which see the same service class as supplied in the parameter. Let's take an example. We have JAXB classes exported by JRE and there is a bundle A which contains JAXB API and implementation. The bundle B is wired to itself for JAXB classes. Assume a user supplied bundle B is wired to JRE's JAXB. When bundle B calls JAXBContext.createContext(JAXBContext.class), JRE's JAXBContext will use this API. The implementation will look for META-INF/services/JAXBContext files and find a file in JAXB bundle. Let's say that file contains com.acme.jaxb.JAXBContextFactory. com.acme.jaxb.ContextFactory does not implement JAXBContext.class. Instead, as per JAXB spec, it must provide some factory methods to create JAXBContext. If our implementation simply returns that class without doing any further tests, a nasty class cast exception is going to be resulted, because user's bundle B uses JAXB from JRE, which means JAXBContext.class is loaded by JRE, yet com.acme.jaxb.JAXBContextFactory uses JAXBContext from bundle A. To avoid such problem, we will try to load JAXBContext using class loader of com.acme.jaxb.JAXBContextFactory and see if that's same as supplied JAXBContext.class. If they are same, we return com.acme.jaxb.JAXBContextFactory, else we don't. In this example, we won't.

Parameters

serviceClass:Class<T>: type of service requested

Returns:Iterable<Class<T>>

classes corresponding to entries in META-INF/services file for the service class.

lookupProviderClasses1	back to summary
pack-priv abstract <T> Iterable<Class<T>> lookupProviderClasses1(Class<T> serviceType)

lookupProviderInstances back to summary

lookupProviderInstances	back to summary
public static <T> Iterable<? extends T> lookupProviderInstances(Class<T> serviceClass) Calling this method is equivalent to calling `lookupProviderInstances(Class, ProviderFactory)` with a null factory object. See Also `lookupProviderInstances(Class, org.glassfish.hk2.osgiresourcelocator.ServiceLoader.ProviderFactory)`

public static <T> Iterable<? extends T> lookupProviderInstances(Class<T> serviceClass)

Calling this method is equivalent to calling lookupProviderInstances(Class, ProviderFactory) with a null factory object.

See Also: lookupProviderInstances(Class, org.glassfish.hk2.osgiresourcelocator.ServiceLoader.ProviderFactory)

lookupProviderInstances	back to summary
public static <T> Iterable<? extends T> lookupProviderInstances(Class<T> serviceClass, ServiceLoader.ProviderFactory<T> factory) Parameters serviceClass:Class<T> type of service requested factory:ServiceLoader.ProviderFactory<T> ProviderFactory used to instantiate provider instance from a provider class. If null is supplied, it calls Class.newInstance to obtain a provider instance from provider class. Returns:Iterable<? extends T> provider instances implementing the given service class.

lookupProviderInstances

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public static <T> Iterable<? extends T> lookupProviderInstances(Class<T> serviceClass, ServiceLoader.ProviderFactory<T> factory)

Parameters

serviceClass:Class<T>: type of service requested
factory:ServiceLoader.ProviderFactory<T>: ProviderFactory used to instantiate provider instance from a provider class. If null is supplied, it calls Class.newInstance to obtain a provider instance from provider class.

Returns:Iterable<? extends T>

provider instances implementing the given service class.

lookupProviderInstances1	back to summary
pack-priv abstract <T> Iterable<? extends T> lookupProviderInstances1(Class<T> serviceType, ServiceLoader.ProviderFactory<T> factory)

reset	back to summary
public static synchronized void reset()

public abstract Class ServiceLoader

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

public Interface ServiceLoader.ProviderFactory<T>

Method Summary

Method Detail