org.hibernate.boot.registry.selector.spi

Interface StrategySelector

All Superinterfaces:

Serializable, Service

public interface StrategySelector
extends Service

Service which acts as a registry for named strategy implementations. <p/> Strategies are more open ended than services, though a strategy managed here might very well also be a service. The strategy is any interface that has multiple, (possibly short) named implementations. <p/> StrategySelector manages resolution of particular implementation by (possibly short) name via the selectStrategyImplementor(java.lang.Class<T>, java.lang.String) method, which is the main contract here. As indicated in the docs of that method the given name might be either a short registered name or the implementation FQN. As an example, consider resolving the TransactionCoordinatorBuilder implementation to use. To use the JDBC-based TransactionCoordinatorBuilder the passed name might be either "jdbc" or "org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorBuilderImpl" (which is the FQN). <p/> Strategy implementations can be managed by registerStrategyImplementor(java.lang.Class<T>, java.lang.String, java.lang.Class<? extends T>) and unRegisterStrategyImplementor(java.lang.Class<T>, java.lang.Class<? extends T>). Originally designed to help the OSGi use case, though no longer used there. <p/> The service also exposes a general typing API via resolveStrategy(java.lang.Class<T>, java.lang.Object) and resolveDefaultableStrategy(java.lang.Class<T>, java.lang.Object, T) which accept implementation references rather than implementation names, allowing for a multitude of interpretations of said "implementation reference". See the docs for resolveDefaultableStrategy(java.lang.Class<T>, java.lang.Object, T) for details.

Method Summary

Modifier and Type	Method and Description
<T> Collection<Class<? extends T>>	getRegisteredStrategyImplementors(Class<T> strategy) Retrieve all of the registered implementors of the given strategy.
<T> void	registerStrategyImplementor(Class<T> strategy, String name, Class<? extends T> implementation) Registers a named implementor of a particular strategy contract.
<T> T	resolveDefaultableStrategy(Class<T> strategy, Object strategyReference, Callable<T> defaultResolver) Resolve strategy instances.
<T> T	resolveDefaultableStrategy(Class<T> strategy, Object strategyReference, T defaultValue) Resolve strategy instances.
<T> T	resolveStrategy(Class<T> strategy, Object strategyReference) Resolve strategy instances.
<T> T	resolveStrategy(Class<T> strategy, Object strategyReference, Callable<T> defaultResolver, StrategyCreator<T> creator)
<T> T	resolveStrategy(Class<T> strategy, Object strategyReference, T defaultValue, StrategyCreator<T> creator)
<T> Class<? extends T>	selectStrategyImplementor(Class<T> strategy, String name) Locate the named strategy implementation.
<T> void	unRegisterStrategyImplementor(Class<T> strategy, Class<? extends T> implementation) Un-registers a named implementor of a particular strategy contract.

Method Detail

registerStrategyImplementor

<T> void registerStrategyImplementor(Class<T> strategy,
                                     String name,
                                     Class<? extends T> implementation)

Registers a named implementor of a particular strategy contract.

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The strategy contract.

name - The registration name

implementation - The implementation Class

unRegisterStrategyImplementor

<T> void unRegisterStrategyImplementor(Class<T> strategy,
                                       Class<? extends T> implementation)

Un-registers a named implementor of a particular strategy contract. Un-registers all named registrations for the given strategy contract naming the given class.

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The strategy contract.

implementation - The implementation Class

selectStrategyImplementor

<T> Class<? extends T> selectStrategyImplementor(Class<T> strategy,
                                                 String name)

Locate the named strategy implementation.

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The type of strategy to be resolved.

name - The name of the strategy to locate; might be either a registered name or the implementation FQN.

Returns:

The named strategy implementation class.

resolveStrategy

<T> T resolveStrategy(Class<T> strategy,
                      Object strategyReference)

Resolve strategy instances. See discussion on resolveDefaultableStrategy(java.lang.Class<T>, java.lang.Object, T). Only difference is that here, the implied default value is null.

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The type (interface) of the strategy to be resolved.

strategyReference - The reference to the strategy for which we need to resolve an instance.

Returns:

The strategy instance

resolveDefaultableStrategy

<T> T resolveDefaultableStrategy(Class<T> strategy,
                                 Object strategyReference,
                                 T defaultValue)

Resolve strategy instances. The incoming reference might be:<ul> <li> null - in which case defaultValue is returned. </li> <li> An actual instance of the strategy type - it is returned, as is </li> <li> A reference to the implementation Class - an instance is created by calling Class.newInstance() (aka, the class’s no-arg ctor). </li> <li> The name of the implementation class - First the implementation’s Class reference is resolved, and then an instance is created by calling Class.newInstance() </li> </ul>

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The type (interface) of the strategy to be resolved.

strategyReference - The reference to the strategy for which we need to resolve an instance.

defaultValue - THe default value to use if strategyReference is null

Returns:

The strategy instance

resolveDefaultableStrategy

<T> T resolveDefaultableStrategy(Class<T> strategy,
                                 Object strategyReference,
                                 Callable<T> defaultResolver)

Resolve strategy instances. The incoming reference might be:<ul> <li> null - in which case defaultValue is returned. </li> <li> An actual instance of the strategy type - it is returned, as is </li> <li> A reference to the implementation Class - an instance is created by calling Class.newInstance() (aka, the class’s no-arg ctor). </li> <li> The name of the implementation class - First the implementation’s Class reference is resolved, and then an instance is created by calling Class.newInstance() </li> </ul>

Type Parameters:

T - The type of the strategy. Used to make sure that the strategy and implementation are type compatible.

Parameters:

strategy - The type (interface) of the strategy to be resolved.

strategyReference - The reference to the strategy for which we need to resolve an instance.

defaultResolver - A strategy for resolving the default value strategyReference resolves to null.

Returns:

The strategy instance

resolveStrategy

<T> T resolveStrategy(Class<T> strategy,
                      Object strategyReference,
                      Callable<T> defaultResolver,
                      StrategyCreator<T> creator)

resolveStrategy

<T> T resolveStrategy(Class<T> strategy,
                      Object strategyReference,
                      T defaultValue,
                      StrategyCreator<T> creator)

getRegisteredStrategyImplementors

<T> Collection<Class<? extends T>> getRegisteredStrategyImplementors(Class<T> strategy)

Retrieve all of the registered implementors of the given strategy. Useful to allow defaulting the choice to the single registered implementor when only one is registered

Returns:

The implementors. Should never return null