Package me.datafox.dfxengine.injector.api.annotation

Annotation Interface Component

@Retention(RUNTIME) @Target({TYPE,METHOD}) public @interface Component

A component is a class that can be injected as a dependency. The Injector looks for all classes and methods annotated as a component. A class will be registered as an injectable dependency, and a method's returned value will be used as one. A class may have either a default constructor or a single constructor annotated with Inject with dependencies as parameters. It may also have non-static and non-final dependency fields annotated with Inject that are injected right after instantiation. Likewise, a component method may have other dependencies as parameters.

If a method is annotated as a component but is void, the method will be invoked after all other invocations (including Initialize methods) and all of its parameters are treated as dependencies like normal. This is useful when you need to validate other components in ways that are not covered by the Injector itself.

value() determines how the component is instantiated. InstantiationPolicy.ONCE creates a singleton instance of the component class at build time, while InstantiationPolicy.PER_INSTANCE instantiates a new instance of the component class for every component that depends on it.

order() determines the priority of components. If a single component is requested but multiple are present, the highest priority component will be used. Only if multiple components with the same priority exist, an exception will be thrown. This also affects the order of components in the List when multiple components are requested.

  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    int
    order
    The order affects both the order of components in the list when multiple components with this component's signature are requested, and the priority when a single component with this component's signature has been requested and multiple components with the same signature are present.
    InstantiationPolicy
    value
    InstantiationPolicy.ONCE means that this component will be instantiated once.

  • Element Details

    • value

      InstantiationPolicy value
      InstantiationPolicy.ONCE means that this component will be instantiated once. InstantiationPolicy.PER_INSTANCE means that this component will be instantiated for every other component that requests it.
      Returns:
      the associated InstantiationPolicy
      Default:
      ONCE

    • order

      int order
      The order affects both the order of components in the list when multiple components with this component's signature are requested, and the priority when a single component with this component's signature has been requested and multiple components with the same signature are present. Lower number means higher priority.
      Returns:
      int used for ordering components
      Default:
      0