Annotations Howto

Turbine provides a number of annotations to inject dependencies into your actions, screens and layouts. All Assemblers that is, all modules of type Action, Screen, Layout, Page, Navigation and ScheduledJob as well as all Valves in the pipeline support the injection of services, configurations and loaders. This relieves you from the burden of looking them up at runtime and thus simplifies and accelerates the code.

The annotation can only be used with a field. A declared field in a class annotated with @TurbineService gets injected an instance of this service at the time the instance of the class is created. The field should have the type of the service interface like in the following two examples: This is the equivalent of As you an see, the annotation supports an optional parameter, the name of the service in the Turbine service repository. If this parameter is not present, the annotation processor will look for the field SERVICE_NAME and then ROLE in the type class of the field to retrieve the service name. If none of them can be found, the fully qualified class name of the service interface is used to look up the service.
If the service instance cannot be found, the annotation processor will throw an exception. The annotation can only be used with a field. If a declared field of the type Configuration is annotated with @TurbineConfiguration, Turbine will inject an instance of the Turbine configuration object at the time the instance of the class is created. This is the equivalent of The annotation supports an optional parameter, the prefix of the configuration subset to retrieve.
If other fields having simple types are annotated with @TurbineConfiguration, Turbine will inject the corresponding configuration value. In this case, the annotation parameter defines the configuration key and is required. Strings, Lists and most simple types are supported. The value will only be set if the key is found in the configuration, so that the field can be initialized with a default value. This is the equivalent of The annotation can only be used with a field. A declared field in a class annotated with @TurbineLoader gets injected an instance of the specified Loader at the time the instance of the class is created. The field should have the type of the loader. This is the equivalent of The annotation parameter is required and defines the type of module that is to be loaded. The annotation can only be used with a method. A method in a class annotated with @TurbineActionEvent is associated to a named action event. The annotation parameter is required and defines the name of the event. See the Action Events Howto for usage and examples. It is important to note that the processing of the annotations at the time the module class is instantiated takes some time. It is therefore strongly recommended to re-use the module instances in a production environment by setting the configuration parameter module.cache to true in TurbineResources.properties.