Package oracle.dbtools.plugin.api.di

Interface InstanceLocator

  • All Known Implementing Classes:
    Instances, Instances.Builder
    public interface InstanceLocator
    Allows the application to dynamically obtain instances of services with a specified combination of required type and qualifiers. In general it is preferred to use injection to resolve dependencies, but in certain situations, injection is not the most convenient way to obtain a service instance. For these cases InstanceProvider should be used. This facility should be used sparingly, frequent use indicates use of the Service Locator Pattern instead of the Dependency Injection Pattern.
    Author:
    cdivilly
    See Also:
    InstanceProvider, TypeQualifier

    • Field Detail

      • INSTANCE_LOCATOR_ATTRIBUTE

        static final java.lang.String INSTANCE_LOCATOR_ATTRIBUTE
        Denotes the name of a HttpServletRequest attribute which if present on a request indicates an attribute whose value will be an instance of InstanceLocator 
         void doGet(final HttpServletRequest request,
     final HttpServletResponse response)
     throws ServletException, IOException {
   // Get request scoped InstanceLocator
   final InstanceLocator locator = (InstanceLocator) request
       .getAttribute(InstanceLocator.INSTANCE_LOCATOR_ATTRIBUTE);
   if (locator != null) {
     final SomeService service = locator.select(SomeService.class);
     // use SomeService instance...
   }
 }

      • INSTANTIATOR_TYPE_SUFFIX

        @Deprecated
static final java.lang.String INSTANTIATOR_TYPE_SUFFIX
        Deprecated.
        The Instantiator concept has been deprecated
        Identifies the expected type name suffix for any type that can instantiate another type. See Accelerating Instantiation for more information on this topic.
        See Also:
        Constant Field Values

    • Method Detail

      • select

        default <T> InstanceProvider<T> select​(java.lang.Class<T> service)
        Select all services matching the specified type. Equivalent to select(TypeQualifier.provides(service)
        Type Parameters:
        T - The type of the service
        Parameters:
        service - The service to resolve
        Returns:
        InstanceProvider for the specified type. This value is never null.
        Since:
        19.3.0

      • select

        @Deprecated
default <T> InstanceProvider<T> select​(java.lang.Class<T> service,
                                       java.lang.annotation.Annotation... qualifiers)
        Deprecated.
        Use select(TypeQualifier) instead
        Obtains a child Instance for the given required type and additional required qualifiers.
        Type Parameters:
        T - The type of the service to locate
        Parameters:
        service - The type (contract) of the service to retrieve
        qualifiers - Additional qualifiers that constrain which implementation to match
        Returns:
        InstanceProvider for the specified type and qualifiers. This value is never null.

      • select

        <T> InstanceProvider<T> select​(TypeQualifier<T> qualifier)
        Select all services matching the specified TypeQualifier
        Type Parameters:
        T - The type of the service to locate
        Parameters:
        qualifier - The qualifier that constrains which implementation to match
        Returns:
        InstanceProvider for the specified type and qualifier. This value is never null.
        Since:
        19.3.0