org.grouplens.grapht.solver

Class DefaultInjector

java.lang.Object

org.grouplens.grapht.solver.DefaultInjector

All Implemented Interfaces:

AutoCloseable, Injector

@ThreadSafe
public class DefaultInjector
extends Object
implements Injector

DefaultInjector is the default Injector implementation. When resolving the dependency graph for a desire, a "context" is built which consists of an ordering of qualified types that satisfy each dependency. The DefaultInjector uses the DependencySolver to manage dependency resolution. New injectors can easily be built to also use this solver.

Author:

GroupLens Research

Constructor Summary

Constructors

Constructor and Description
DefaultInjector(BindingFunction... functions) Create a new DefaultInjector.
DefaultInjector(CachePolicy defaultPolicy, BindingFunction... functions) Create a new DefaultInjector.
DefaultInjector(CachePolicy defaultPolicy, int maxDepth, BindingFunction... functions) Create a new DefaultInjector.

Method Summary

Modifier and Type	Method and Description
void	close() Close the injector, shutting down any instantiated components that require shutdown.
<T> T	getInstance(Annotation qualifier, Class<T> type) Get an instance of T with the given Qualifier annotation.
<T> T	getInstance(Class<T> type) Get an instance of T based on the bindings that this Injector was configured with.
DependencySolver	getSolver()
<T> T	tryGetInstance(Annotation qualifier, Class<T> type) Try to get an instance of a component, returning null if the component does not have a configured implementation.

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultInjector

public DefaultInjector(BindingFunction... functions)

Create a new DefaultInjector. The created resolver will use a max dependency depth of 100 to estimate if there are cycles in the dependency hierarchy. Bindings with a NO_PREFERENCE cache policy will be treated as NEW_INSTANCE.

Parameters:

functions - The BindingFunctions to use, ordered with highest priority function first

Throws:

NullPointerException - if spi or functions ar enull

DefaultInjector

public DefaultInjector(CachePolicy defaultPolicy,
                       BindingFunction... functions)

Create a new DefaultInjector. The created resolver will use a max dependency depth of 100 to estimate if there are cycles in the dependency hierarchy. Bindings with a NO_PREFERENCE cache policy will use defaultPolicy.

Parameters:

defaultPolicy - The CachePolicy used in place of NO_PREFERENCE

functions - The BindingFunctions to use, ordered with highest priority functions first

Throws:

IllegalArgumentException - if defaultPolicy is NO_PREFERENCE

NullPointerException - if spi or functions are null

DefaultInjector

public DefaultInjector(CachePolicy defaultPolicy,
                       int maxDepth,
                       BindingFunction... functions)

Create a new DefaultInjector. maxDepth represents the maximum depth of the dependency hierarchy before it is assume that there is a cycle. Bindings with a NO_PREFERENCE cache policy will use defaultPolicy.

This constructor can be used to increase this depth in the event that configuration requires it, although for most purposes the default 100 should be sufficient.

Parameters:

defaultPolicy - The CachePolicy used in place of NO_PREFERENCE

maxDepth - The maximum depth of the dependency hierarchy

functions - The BindingFunctions to use, ordered with highest priority functions first

Throws:

IllegalArgumentException - if maxDepth is less than 1, or if defaultPolicy is NO_PREFERENCE

NullPointerException - if spi or functions are null

Method Detail

getSolver

public DependencySolver getSolver()

Returns:

The DependencySolver backing this injector

getInstance

@Nonnull
public <T> T getInstance(Class<T> type)
                            throws InjectionException

Description copied from interface: Injector

Get an instance of T based on the bindings that this Injector was configured with. An exception is thrown if the request type cannot be instantiated with dependency injection.

Injectors may memoize or cache previously created objects. As an example, the Injector created by InjectorBuilder reuses instances where possible.

Specified by:

getInstance in interface Injector

Type Parameters:

T - The object type being created

Parameters:

type - The class type

Returns:

An instance of type T

Throws:

ConstructionException - if type cannot be instantiated

InjectionException

getInstance

@Nonnull
public <T> T getInstance(Annotation qualifier,
                                   Class<T> type)
                            throws InjectionException

Description copied from interface: Injector

Get an instance of T with the given Qualifier annotation.

Specified by:

getInstance in interface Injector

Type Parameters:

T - The object type

Parameters:

qualifier - The qualifier on of the returned instance

type - The class type

Returns:

An instance of type T

Throws:

ConstructionException - if type cannot be instantiated

InjectionException

tryGetInstance

@Nullable
public <T> T tryGetInstance(Annotation qualifier,
                                       Class<T> type)
                                throws InjectionException

Description copied from interface: Injector

Try to get an instance of a component, returning null if the component does not have a configured implementation.

Specified by:

tryGetInstance in interface Injector

Type Parameters:

T - The component type.

Parameters:

qualifier - The qualifier, or null for an unqualified component.

type - The component type.

Returns:

An instance of type T, or null if no implemenation of T is configured.

Throws:

InjectionException - if there is some other error injecting the instance.

close

public void close()

Description copied from interface: Injector

Close the injector, shutting down any instantiated components that require shutdown.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Injector