Interface StrategySelector
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- 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 theselectStrategyImplementor(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 theTransactionCoordinatorBuilder
implementation to use. To use the JDBC-basedTransactionCoordinatorBuilder
the passed name might be either"jdbc"
or"org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorBuilderImpl"
.Strategy implementations can be managed by
registerStrategyImplementor(java.lang.Class<T>, java.lang.String, java.lang.Class<? extends T>)
andunRegisterStrategyImplementor(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)
andresolveDefaultableStrategy(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 forresolveDefaultableStrategy(java.lang.Class<T>, java.lang.Object, T)
for details.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method 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, @Nullable 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.
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Method Detail
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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 nameimplementation
- The implementation Class
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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
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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.
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resolveStrategy
<T> T resolveStrategy(Class<T> strategy, @Nullable Object strategyReference)
Resolve strategy instances. See discussion onresolveDefaultableStrategy(java.lang.Class<T>, java.lang.Object, T)
. Only difference is that here, the implied default value isnull
.- 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
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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
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A reference to the implementation
Class
- an instance is created by callingClass.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 callingClass.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
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resolveDefaultableStrategy
<T> T resolveDefaultableStrategy(Class<T> strategy, Object strategyReference, Callable<T> defaultResolver)
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
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A reference to the implementation
Class
- an instance is created by callingClass.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 callingClass.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.defaultResolver
- A strategy for resolving the default value strategyReference resolves to null.- Returns:
- The strategy instance
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resolveStrategy
<T> T resolveStrategy(Class<T> strategy, Object strategyReference, Callable<T> defaultResolver, StrategyCreator<T> creator)
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resolveStrategy
<T> T resolveStrategy(Class<T> strategy, Object strategyReference, T defaultValue, StrategyCreator<T> creator)
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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
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