Package 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 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".

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 Details

    • 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, @Nullable 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

    • 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
      • 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.
      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