Package org.elasticsearch.common.inject

Interface Binding<T>

Type Parameters:
T - the bound type. The injected is always assignable to this type.
All Superinterfaces:
Element
All Known Subinterfaces:
ConstructorBinding<T>, ConvertedConstantBinding<T>, ExposedBinding<T>, InstanceBinding<T>, LinkedKeyBinding<T>, ProviderBinding<T>, ProviderInstanceBinding<T>, ProviderKeyBinding<T>, UntargettedBinding<T>
All Known Implementing Classes:
BindingImpl, ExposedBindingImpl, InstanceBindingImpl, LinkedBindingImpl, LinkedProviderBindingImpl, ProviderInstanceBindingImpl, UntargettedBindingImpl
public interface Binding<T> extends Element
A mapping from a key (type and optional annotation) to the strategy for getting instances of the type. This interface is part of the introspection API and is intended primarily for use by tools.

Bindings are created in several ways:

  • Explicitly in a module, via bind() and bindConstant() statements: 
         bind(Service.class).annotatedWith(Red.class).to(ServiceImpl.class);
     bindConstant().annotatedWith(ServerHost.class).to(args[0]);
  • Implicitly by the Injector by following a type's pointer annotations or by using its annotated or default constructor.
  • By converting a bound instance to a different type.
  • For providers, by delegating to the binding for the provided type.

They exist on both modules and on injectors, and their behaviour is different for each:

  • Module bindings are incomplete and cannot be used to provide instances. This is because the applicable scopes and interceptors may not be known until an injector is created. From a tool's perspective, module bindings are like the injector's source code. They can be inspected or rewritten, but this analysis must be done statically.
  • Injector bindings are complete and valid and can be used to provide instances. From a tools' perspective, injector bindings are like reflection for an injector. They have full runtime information, including the complete graph of injections necessary to satisfy a binding.

  • Method Details

    • getKey

      Key<T> getKey()
      Returns the key for this binding.

    • getProvider

      Provider<T> getProvider()
      Returns the scoped provider guice uses to fulfill requests for this binding.
      Throws:
      UnsupportedOperationException - when invoked on a Binding created via Elements.getElements(org.elasticsearch.common.inject.Module...). This method is only supported on Bindings returned from an injector.

    • acceptTargetVisitor

      <V> V acceptTargetVisitor(BindingTargetVisitor<? super T,V> visitor)
      Accepts a target visitor. Invokes the visitor method specific to this binding's target.
      Parameters:
      visitor - to call back on
      Since:
      2.0

    • acceptScopingVisitor

      <V> V acceptScopingVisitor(BindingScopingVisitor<V> visitor)
      Accepts a scoping visitor. Invokes the visitor method specific to this binding's scoping.
      Parameters:
      visitor - to call back on
      Since:
      2.0