Package com.gruelbox.transactionoutbox

Interface Instantiator

All Known Implementing Classes:
AbstractFullyQualifiedNameInstantiator
public interface Instantiator
Provides callbacks for the creation and serialization of classes by TransactionOutbox.

  • Method Details

    • usingReflection

      static Instantiator usingReflection()
      Creates an Instantiator which records the class name as its fully qualified name (e.g. com.gruelbox.example.EnterpriseBeanProxyFactoryFactory) and instantiates instances using reflection and a no-args constructor.

      This is the default used by TransactionOutbox if nothing else is specified.

      Returns:
      A reflection instantiator

    • using

      static Instantiator using(Function<Class<?>,Object> fn)
      Creates an Instantiator which records the class name as its fully qualified name (e.g. com.gruelbox.example.EnterpriseBeanProxyFactoryFactory) and instantiates instances using the supplied function, which takes the fully qualified name and should return an instance.

      This is a good option to use with dependency injection frameworks such as Guice: 

      TransactionOutbox outbox = TransactionOutbox.builder()
 ...
 .instantiator(Instantiator.using(injector::getInstance))
 .build();
      Parameters:
      fn - A function to create an instance of the specified class.
      Returns:
      A reflection instantiator

    • getName

      String getName(Class<?> clazz)
      Provides the name of the specified class. This may be the classes fully-qualified name, or may be an alias of some kind. This is up to the implementer.

      Not using the actual class name can be useful in avoiding a case where queued tasks end up referencing renamed classes following a refactor. It is also useful for DI frameworks such as Spring DI, which use named bindings by default.

      Parameters:
      clazz - The class to get the name of.
      Returns:
      The class name.

    • getInstance

      Object getInstance(String name)
      Requests an instance of the named class, where the "name" is whatever is returned by getName(Class).

      A common use-case for this method is to return a class from a DI framework such as Guice (using an injected {code Injector}), but it is perfectly valid to simply instantiate the class by name and populate its dependencies directly.

      Parameters:
      name - The class "name" as returned by getName(Class).
      Returns:
      An instance of the class.