org.hibernate.boot.registry.selector.spi

Interface StrategySelector

All Superinterfaces:

Serializable, Service

All Known Implementing Classes:

StrategySelectorImpl

public interface StrategySelector
extends Service

Service which acts as a registry for named strategy implementations.

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.

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 TransactionFactory implementation to use. To use the JDBC-based TransactionFactory the passed name might be either "jdbc" or "org.hibernate.engine.transaction.internal.jdbc.JdbcTransactionFactory" (which is the FQN).

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.

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

Methods

Modifier and Type	Method and Description
<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, T defaultValue) Resolve strategy instances.
<T> T	resolveStrategy(Class<T> strategy, Object strategyReference) Resolve strategy instances.
<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:

• null - in which case defaultValue is returned.
• An actual instance of the strategy type - it is returned, as is
• A reference to the implementation Class - an instance is created by calling Class.newInstance() (aka, the class's no-arg ctor).
• The name of the implementation class - First the implementation's Class reference is resolved, and then an instance is created by calling Class.newInstance()

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