org.apache.tapestry5.ioc
Interface ObjectProvider

All Known Implementing Classes:

ApplicationMessageCatalogObjectProvider, AssetObjectProvider, AutobuildObjectProvider, EntityManagerObjectProvider, ServiceAnnotationObjectProvider, StaticObjectProvider, SymbolObjectProvider, ValueObjectProvider

public interface ObjectProvider

Object providers represent an alternate way to locate an object provided somewhere in the Registry. Instead of using a just the service id to gain access to a service within the Registry, object providers in different flavors are capable of vending, or even creating, objects of disparate types from disparate sources.

Object providers are consulted in a strict order, and the first non-null result is taken.

In many cases, an object provider searches for additional annotations on the element (usually a parameter, or perhaps a field) for which a value is required.

Method Summary

<T> T

provide(Class<T> objectType, AnnotationProvider annotationProvider, ObjectLocator locator) Provides an object based on an expression.

Method Detail

provide

<T> T provide(Class<T> objectType,
              AnnotationProvider annotationProvider,
              ObjectLocator locator)

Provides an object based on an expression. The process of providing objects occurs within a particular context, which will typically be a service builder method, service contributor method, or service decorator method. The locator parameter provides access to the services visible to that context.

Type Parameters:

T -

Parameters:

objectType - the expected object type

annotationProvider - provides access to annotations (typically, the field or parameter to which an injection-related annotation is attached); annotations on the field or parameter may also be used when resolving the desired object

locator - locator for the context in which the provider is being used

Returns:

the requested object, or null if this object provider can not supply an object

Throws:

RuntimeException - if the expression can not be evaluated, or the type of object identified is not assignable to the type specified by the objectType parameter