com.sun.hk2.component
Class ExistingSingletonInhabitant<T>

java.lang.Object
  com.sun.hk2.component.AbstractInhabitantImpl<T>
      com.sun.hk2.component.ExistingSingletonInhabitant<T>

All Implemented Interfaces:

Holder<T>, Binding<T>, Factory<T>, ManagedComponentProvider<T>, Provider<T>, Inhabitant<T>

public class ExistingSingletonInhabitant<T>
extends AbstractInhabitantImpl<T>

Inhabitant built around an object that already exists.

Author:

Kohsuke Kawaguchi

Nested Class Summary

Nested classes/interfaces inherited from interface com.sun.hk2.component.Holder

Holder.Impl<T>

Field Summary

Fields inherited from class com.sun.hk2.component.AbstractInhabitantImpl

descriptor, logger

Constructor Summary

ExistingSingletonInhabitant(Class<T> type, T object)

ExistingSingletonInhabitant(Class<T> type, T object, MultiMap<String,String> metadata)

ExistingSingletonInhabitant(T object)

Method Summary

T	get(Inhabitant onBehalfOf) Returns the instance of this inhabitant.
boolean	isActive()
MultiMap<String,String>	metadata() Gets the metadata associated with this inhabitant.
void	release() Called to orderly shutdown Habitat.
String	toString()
Class<T>	type() Type of the inhabitant.
String	typeName() The short-cut for type().getName() but this allows us to defer loading the actual types.

Methods inherited from class com.sun.hk2.component.AbstractInhabitantImpl

companions, dispose, get, getAnnotation, getAnnotation, getAnnotations, getDescriptor, getDescriptorFor, getProvider, getProvider, getSerializedMetadata, getSerializedMetadata, lead, matches, setCompanions

Methods inherited from class java.lang.Object

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

Constructor Detail

ExistingSingletonInhabitant

public ExistingSingletonInhabitant(T object)

ExistingSingletonInhabitant

public ExistingSingletonInhabitant(Class<T> type,
                                   T object)

ExistingSingletonInhabitant

public ExistingSingletonInhabitant(Class<T> type,
                                   T object,
                                   MultiMap<String,String> metadata)

Method Detail

toString

public String toString()

Overrides:

toString in class AbstractInhabitantImpl<T>

typeName

public String typeName()

Description copied from interface: Inhabitant

The short-cut for type().getName() but this allows us to defer loading the actual types.

type

public Class<T> type()

Description copied from interface: Inhabitant

Type of the inhabitant.

The only binding contract that needs to be honored is that the Inhabitant.get() method returns an instance assignable to this type. That is, get().getClass()==type() doesn't necessarily have to hold, but type().isInstance(get()) must.

This is particularly true when Factory is involved, as in such case HK2 has no way of knowing the actual type. That said, this method is not designed for the semantics of contract/implementation split --- implementations of a contract should return the concrete type from this method, and use habitat index to support look-up by contract.

Returns:

Always non-null, same value.

metadata

public MultiMap<String,String> metadata()

Description copied from interface: Inhabitant

Gets the metadata associated with this inhabitant.

This data is usually used by a sub-system of HK2, and not really meant to be used by applications. (At least for now.) The main benefit of metadata is that it's available right away as soon as the Habitat is properly initialized, even before component classes are loaded. In contrast, accessing annotations would require classes to be loaded and resolved.

Returns:

can be empty but never null. The values are read-only.

See Also:

Service.metadata()

get

public T get(Inhabitant onBehalfOf)
      throws ComponentException

Description copied from interface: Inhabitant

Returns the instance of this inhabitant.

THIS METHOD SHOULD BE ONLY USED BY HK2 IMPLEMENTATION.

Inhabitants are often used with the decorator pattern (see AbstractCreatorInhabitantImpl for example), yet during the object initializtion inside the Inhabitant.get() method, we often need the reference to the outer-most Inhabitant registered to the Habitat (for example so that we can request the injection of {link Inhabita} that represents itself, or to inject companions.)

So this overloaded version of the get method takes the outer-most Inhabitant. This method is only invoked from within HK2 where the decorator pattern is used.

Throws:

ComponentException

isActive

public boolean isActive()

release

public void release()

Description copied from interface: Inhabitant

Called to orderly shutdown Habitat.

The expected behavior is for objects to get its PreDestroy callback invoked, and its reference released. For singleton objects, this method is expected to dispose that object.

For scoped objects, those are released when ScopeInstance.release() is invoked.