net.sf.jguiraffe.di.impl.providers

Class CollectionBeanProvider

java.lang.Object

net.sf.jguiraffe.di.impl.providers.SimpleBeanProvider

net.sf.jguiraffe.di.impl.providers.CollectionBeanProvider

All Implemented Interfaces:

BeanProvider

Direct Known Subclasses:

ListBeanProvider, SetBeanProvider

public abstract class CollectionBeanProvider
extends SimpleBeanProvider

An abstract base class for BeanProvider implementations that create beans derived from collections.

This bean provider base implementation can be used when collection beans are to be created. What makes collections a bit special is the fact that their elements are also dependencies, which can reference other beans. So this bean provider has to ensure that all dependencies are registered correctly, so they can be resolved when the collection is created.

This class implements the major part of the functionality required for creating collection beans. It is initialized with a collection of dependencies representing the elements of the final collection. These can be either constant dependencies or references to other beans. In the getBean() implementation a collection of the correct type is created, the element dependencies are resolved, and the resulting objects are added to the collection.

A concrete subclass is responsible for creating a collection of a specific type. For this purpose the createCollection() method has to be defined. It is invoked by getBean() for obtaining a new instance of the collection class supported.

Bean providers of this type are intended to be used together with a LifeCycleBeanProvider that controls the creation of new instances.

Implementation note: Objects of this class are immutable and thus can be shared between multiple threads.

Version:

$Id: CollectionBeanProvider.java 205 2012-01-29 18:29:57Z oheger $

Author:

Oliver Heger

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CollectionBeanProvider(Collection<Dependency> deps) Creates a new instance of CollectionBeanProvider and initializes it with a collection with the dependencies of the elements.

Method Summary

Modifier and Type	Method and Description
protected abstract Collection<Object>	createCollection(int size) Creates the collection.
Object	getBean(DependencyProvider dependencyProvider) Returns the bean managed by this provider.
Class<?>	getBeanClass(DependencyProvider dependencyProvider) Returns the class of the bean created by this provider.
Set<Dependency>	getDependencies() Returns a set with the dependencies of this bean provider.
Collection<Dependency>	getElementDependencies() Returns a collection with the dependencies of the collection elements.

Methods inherited from class net.sf.jguiraffe.di.impl.providers.SimpleBeanProvider

getLockID, isBeanAvailable, setLockID, shutdown

Methods inherited from class java.lang.Object

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

Constructor Detail

CollectionBeanProvider

protected CollectionBeanProvider(Collection<Dependency> deps)

Creates a new instance of CollectionBeanProvider and initializes it with a collection with the dependencies of the elements.

Parameters:

deps - a collection with the element dependencies (must not be null)

Throws:

IllegalArgumentException - if the collection is null

Method Detail

getElementDependencies

public Collection<Dependency> getElementDependencies()

Returns a collection with the dependencies of the collection elements. From these dependencies the collection will be populated. Note that the collection returned by this method is immutable.

Returns:

a collection with the dependencies of the elements

getBean

public Object getBean(DependencyProvider dependencyProvider)

Returns the bean managed by this provider. This implementation creates a new collection by calling createCollection(). Then the dependencies for the elements are resolved and added to the collection.

Parameters:

dependencyProvider - the dependency provider

Returns:

the bean managed by this provider

getBeanClass

public Class<?> getBeanClass(DependencyProvider dependencyProvider)

Returns the class of the bean created by this provider. This implementation simply returns Collection.class. We expect that collection beans are not so specific that they are queried by class.

Parameters:

dependencyProvider - the dependency provider

Returns:

the class of the bean created by this provider

getDependencies

public Set<Dependency> getDependencies()

Returns a set with the dependencies of this bean provider. This implementation creates a new set from the collection with the dependencies for the elements.

Specified by:

getDependencies in interface BeanProvider

Overrides:

getDependencies in class SimpleBeanProvider

Returns:

the dependencies of this bean provider

See Also:

Dependency

createCollection

protected abstract Collection<Object> createCollection(int size)

Creates the collection. This method is invoked whenever a new bean instance is to be created. Derived classes must here return a new instance of the collection supported.

Parameters:

size - the initial size of the new collection; here the number of elements is passed in

Returns:

the collection