sirius.kernel.di

Class Injector

java.lang.Object

sirius.kernel.di.Injector

public class Injector
extends Object

Central class for collecting and injecting dependencies (which are called parts).

Contains the micro kernel which keeps track of all parts and injects them where required. We consider this a micro kernel, as it doesn't directly know any annotations. It rather delegates the work to classes which implement defined interfaces. Therefore the implementation is rather short but easily extensible.

Parts are commonly added via subclasses of ClassLoadAction. These scan each class in the classpath and instantiate and insert them into the MutableGlobalContext if required. Most of these ClassLoadAction implementations trigger on annotations. A prominent example is the AutoRegisterAction which loads all classes wearing the .Register annotation. Subclasses of ClassLoadAction are discovered automatically.

Accessing parts can be done in two ways. First, one can access the current GlobalContext via context(). This can be used to retrieve parts by class or by class and name. The second way to access parts is to use marker annotations like Part, Parts or Context. Again, these annotations are not processed by the micro kernel itself, but by subclasses of FieldAnnotationProcessor. To process all annotations of a given Java object, GlobalContext.wire(Object) can be used. This will be automatically called for each part which is auto-instantiated by a ClassLoadAction.

Also all annotations on static fields are processed on system startup. This is a simple trick to pass a part to objects which are frequently created and destroyed.

Field Summary

Fields

Modifier and Type	Field and Description
static Log	LOG Logger used by the injection framework.

Method Summary

Modifier and Type	Method and Description
static GlobalContext	context() Provides access to the global context, containing all parts This can also be loaded into a class field using the Context annotation
static List<Class<?>>	getAllLoadedClasses() Returns a list of all loaded classes.
static void	init(Classpath classpath) Initializes the framework.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

public static final Log LOG

Logger used by the injection framework. This is public so that annotation processors in sub packages can log through this logger.

Method Detail

init

public static void init(@Nonnull
                        Classpath classpath)

Initializes the framework. Must be only called once on system startup.

This is automatically invoked by Sirius.start(sirius.kernel.Setup).

Parameters:

classpath - the classpath used to enumerate all classes to be scanned

context

public static GlobalContext context()

Provides access to the global context, containing all parts

This can also be loaded into a class field using the Context annotation

Returns:

the global context containing all parts known to the system

getAllLoadedClasses

public static List<Class<?>> getAllLoadedClasses()

Returns a list of all loaded classes.

Returns:

a list of all classes detected at system startup