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package org.glassfish.hk2.api;
import java.lang.annotation.Annotation;
import org.jvnet.hk2.annotations.Contract;
/**
* An implementation of this must be put into the system in order to
* create contextual instances of services. If there is more than
* one active implementation available for the same scope on the same
* thread a runtime exception will be thrown when the scope is accessed.
*
* An implementation of Context must be in the Singleton scope
*
* @author jwells
* @param This must be the type for which this is a context. For example,
* if your scope is SecureScope, then your context must implement Context<SecureScope>
*
*/
@Contract
public interface Context {
/**
* The scope for which this is the context
*
* @return may not return null, must return the
* scope for which this is a context
*/
public Class getScope();
/**
* Creates a contextual instance of this ActiveDescriptor by calling its
* create method if there is no other matching contextual instance. If there
* is already a contextual instance it is returned. If parent is null then this
* must work like the find call
*
* @param activeDescriptor The descriptor to use when creating instances
* @param root The extended provider for the outermost parent being created
*
* @return A context instance. This value may NOT be null
*/
public U findOrCreate(ActiveDescriptor activeDescriptor, ServiceHandle root);
/**
* Determines if this context has a value for the given key
*
* @param descriptor The descriptor to look for in this context
* @return true if this context has a value associated with this descriptor
*/
public boolean containsKey(ActiveDescriptor descriptor);
/**
* This method is called when {@link ServiceHandle#destroy()} method is called.
* It is up to the context implementation whether or not to honor this destruction
* request based on the lifecycle requirements of the context
*
* @param descriptor A non-null descriptor upon which {@link ServiceHandle#destroy()}
* has been called
*/
public void destroyOne(ActiveDescriptor descriptor);
/**
* Returns true if the findOrCreate method can return null
*
* @return true if null is a legal value from the findOrCreate method
*/
public boolean supportsNullCreation();
/**
* True if this context is active, false otherwise
*
* @return true if this context is active, false otherwise
*/
public boolean isActive();
/**
* Shut down this context.
*/
public void shutdown();
}