org.picocontainer.parameters
Class CollectionComponentParameter

java.lang.Object
  org.picocontainer.parameters.CollectionComponentParameter

All Implemented Interfaces:

Serializable, Parameter

public class CollectionComponentParameter
extends Object
implements Parameter, Serializable

A CollectionComponentParameter should be used to support inject an Array, a Collectionor Mapof components automatically. The collection will contain all components of a special type and additionally the type of the key may be specified. In case of a map, the map's keys are the one of the component adapter.

Author:

Aslak Hellesøy, Jörg Schaible

See Also:

Serialized Form

Field Summary

static CollectionComponentParameter	ARRAY Use ARRAY as Parameterfor an Array that must have elements.
static CollectionComponentParameter	ARRAY_ALLOW_EMPTY Use ARRAY_ALLOW_EMPTY as Parameterfor an Array that may have no elements.

Fields inherited from interface org.picocontainer.Parameter

DEFAULT, ZERO

Constructor Summary

CollectionComponentParameter()
Expect an Arrayof an appropriate type as parameter.

CollectionComponentParameter(boolean emptyCollection)
Expect an Arrayof an appropriate type as parameter.

CollectionComponentParameter(Class componentValueType, boolean emptyCollection)
Expect any of the collection types Array,Collectionor Mapas parameter.

CollectionComponentParameter(Class componentKeyType, Class componentValueType, boolean emptyCollection)
Expect any of the collection types Array,Collectionor Mapas parameter.

Method Summary

void	accept(PicoVisitor visitor) Visit the current Parameter.
protected boolean	evaluate(ComponentAdapter adapter) Evaluate whether the given component adapter will be part of the collective type.
protected Map<Object,ComponentAdapter<?>>	getMatchingComponentAdapters(PicoContainer container, ComponentAdapter adapter, Class keyType, Class valueType) Collect the matching ComponentAdapter instances.
boolean	isResolvable(PicoContainer container, ComponentAdapter adapter, Class expectedType, ParameterName expectedParameterName) Check for a successful dependency resolution of the parameter for the expected type.
Object	resolveInstance(PicoContainer container, ComponentAdapter adapter, Class expectedType, ParameterName expectedParameterName) Resolve the parameter for the expected type.
void	verify(PicoContainer container, ComponentAdapter adapter, Class expectedType, ParameterName expectedParameterName) Verify a successful dependency resolution of the parameter for the expected type.

Methods inherited from class java.lang.Object

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

Field Detail

ARRAY

public static final CollectionComponentParameter ARRAY

Use ARRAY as Parameterfor an Array that must have elements.

ARRAY_ALLOW_EMPTY

public static final CollectionComponentParameter ARRAY_ALLOW_EMPTY

Use ARRAY_ALLOW_EMPTY as Parameterfor an Array that may have no elements.

Constructor Detail

CollectionComponentParameter

public CollectionComponentParameter()

Expect an Arrayof an appropriate type as parameter. At least one component of the array's component type must exist.

CollectionComponentParameter

public CollectionComponentParameter(boolean emptyCollection)

Expect an Arrayof an appropriate type as parameter.

Parameters:

emptyCollection - true if an empty array also is a valid dependency resolution.

CollectionComponentParameter

public CollectionComponentParameter(Class componentValueType,
                                    boolean emptyCollection)

Expect any of the collection types Array,Collectionor Mapas parameter.

Parameters:

componentValueType - the type of the components (ignored in case of an Array)

emptyCollection - true if an empty collection resolves the dependency.

CollectionComponentParameter

public CollectionComponentParameter(Class componentKeyType,
                                    Class componentValueType,
                                    boolean emptyCollection)

Expect any of the collection types Array,Collectionor Mapas parameter.

Parameters:

componentKeyType - the type of the component's key

componentValueType - the type of the components (ignored in case of an Array)

emptyCollection - true if an empty collection resolves the dependency.

Method Detail

resolveInstance

public Object resolveInstance(PicoContainer container,
                              ComponentAdapter adapter,
                              Class expectedType,
                              ParameterName expectedParameterName)

Resolve the parameter for the expected type. The method will return null If the expected type is not one of the collection types Array, Collectionor Map. An empty collection is only a valid resolution, if the emptyCollection flag was set.

Specified by:

resolveInstance in interface Parameter

Parameters:

container - the container from which dependencies are resolved.

adapter - the ComponentAdapter that is asking for the instance

expectedType - the type that the returned instance needs to match.

expectedParameterName - Expected parameter name

Returns:

the instance of the collection type or null

Throws:

PicoCompositionException - if a referenced component could not be instantiated.

isResolvable

public boolean isResolvable(PicoContainer container,
                            ComponentAdapter adapter,
                            Class expectedType,
                            ParameterName expectedParameterName)

Check for a successful dependency resolution of the parameter for the expected type. The dependency can only be satisfied if the expected type is one of the collection types Array,Collectionor Map. An empty collection is only a valid resolution, if the emptyCollection flag was set.

Specified by:

isResolvable in interface Parameter

Parameters:

container - the container from which dependencies are resolved.

adapter - the ComponentAdapter that is asking for the instance

expectedType - the required type

expectedParameterName - Expected parameter name

Returns:

true if matching components were found or an empty collective type is allowed

verify

public void verify(PicoContainer container,
                   ComponentAdapter adapter,
                   Class expectedType,
                   ParameterName expectedParameterName)

Verify a successful dependency resolution of the parameter for the expected type. The method will only return if the expected type is one of the collection types Array, Collectionor Map. An empty collection is only a valid resolution, if the emptyCollection flag was set.

Specified by:

verify in interface Parameter

Parameters:

container - the container from which dependencies are resolved.

adapter - the ComponentAdapter that is asking for the verification

expectedType - the required type

expectedParameterName - Expected parameter name

Throws:

PicoCompositionException - if parameter and its dependencies cannot be resolved

accept

public void accept(PicoVisitor visitor)

Visit the current Parameter.

Specified by:

accept in interface Parameter

Parameters:

visitor - the visitor.

See Also:

Parameter.accept(org.picocontainer.PicoVisitor)

evaluate

protected boolean evaluate(ComponentAdapter adapter)

Evaluate whether the given component adapter will be part of the collective type.

Parameters:

adapter - a ComponentAdapter value

Returns:

true if the adapter takes part

getMatchingComponentAdapters

protected Map<Object,ComponentAdapter<?>> getMatchingComponentAdapters(PicoContainer container,
                                                                       ComponentAdapter adapter,
                                                                       Class keyType,
                                                                       Class valueType)

Collect the matching ComponentAdapter instances.

Parameters:

container - container to use for dependency resolution

adapter - ComponentAdapter to exclude

keyType - the compatible type of the key

valueType - the compatible type of the addComponent

Returns:

a Map with the ComponentAdapter instances and their component keys as map key.