Package net.sf.jguiraffe.di.impl.providers

Class SingletonBeanProvider

java.lang.Object

net.sf.jguiraffe.di.impl.providers.LifeCycleBeanProvider

net.sf.jguiraffe.di.impl.providers.SingletonBeanProvider

All Implemented Interfaces:

BeanInitializer, BeanProvider

public class SingletonBeanProvider
extends LifeCycleBeanProvider

A specialized life-cycle supporting BeanProvider implementation for creating singleton beans.

When the getBean() method of an instance of this class is called for the first time, all dependencies are resolved, and a new bean instance is created (using the specified creation bean provider). Following calls to getBean() always return this same bean instance. In fact, this provider then behaves like a constant bean provider: it does not declare any dependencies any more and does not need any synchronization support (i.e. the getLockID() method will always return null). This means that providers of this type can be efficiently used in a multi-threaded environment once they are initialized.

Instances of this class can also be initialized with an Invokable to be called when the bean is no more needed. This Invokable is triggered by the shutdown() method. This mechanism makes it possible to perform cleanup when a bean store is closed.

Version:

$Id: SingletonBeanProvider.java 208 2012-02-11 20:57:33Z oheger $

Author:

Oliver Heger

Constructor Summary

Constructors

Constructor	Description
SingletonBeanProvider(BeanProvider createProvider)	Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance.
SingletonBeanProvider(BeanProvider createProvider, Invokable initinv)	Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance and the invocation object for performing initialization.
SingletonBeanProvider(BeanProvider createProvider, Invokable initInv, Invokable shutdownInv)	Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance and Invokable objects for initializing and releasing the bean managed by this provider.

Method Summary

Modifier and Type	Method	Description
Object	getBean(DependencyProvider dependencyProvider)	Returns the bean managed by this bean provider.
Set<Dependency>	getDependencies()	Returns the dependencies of this bean provider.
Long	getLockID()	Returns the ID of the locking transaction.
Invokable	getShutdownHandler()	Returns the Invokable object that is called when this provider is shut down.
void	shutdown(DependencyProvider depProvider)	Tells this provider that it is no more needed.

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

canInitialize, createBean, doCreateBean, fetchBean, fetchInitializedBeanInstance, getBeanClass, getBeanCreator, getBeanInitializer, hasBean, initBean, initialize, isBeanAvailable, resetBean, setLockID, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

SingletonBeanProvider

public SingletonBeanProvider(BeanProvider createProvider,
                             Invokable initInv,
                             Invokable shutdownInv)

Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance and Invokable objects for initializing and releasing the bean managed by this provider.

Parameters:

createProvider - the bean provider used for creating a new bean instance (must not be null)

initInv - the (optional) invocation object for performing initialization

shutdownInv - the (optional) Invokable object to be called on shutdown

Throws:

IllegalArgumentException - if the bean provider is undefined

SingletonBeanProvider

public SingletonBeanProvider(BeanProvider createProvider,
                             Invokable initinv)

Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance and the invocation object for performing initialization.

Parameters:

createProvider - the bean provider used for creating a new bean instance (must not be null)

initinv - the (optional) invocation object for performing initialization

Throws:

IllegalArgumentException - if the bean provider is undefined

SingletonBeanProvider

public SingletonBeanProvider(BeanProvider createProvider)

Creates a new instance of SingletonBeanProvider and initializes it with the bean provider for creating a bean instance.

Parameters:

createProvider - the bean provider used for creating a new bean instance (must not be null)

Throws:

IllegalArgumentException - if the bean provider is undefined

Method Detail

getShutdownHandler

public Invokable getShutdownHandler()

Returns the Invokable object that is called when this provider is shut down. This can be null if no shutdown handler was set.

Returns:

the Invokable to be called on shutdown

getBean

public Object getBean(DependencyProvider dependencyProvider)

Returns the bean managed by this bean provider. This implementation will create a bean on first access and then always return this instance.

Parameters:

dependencyProvider - the dependency provider

Returns:

the bean managed by this provider

Throws:

InjectionException - if an error occurs

getDependencies

public Set<Dependency> getDependencies()

Returns the dependencies of this bean provider. If already a bean has been created, this implementation returns null because there is no need any more for resolving dependencies.

Specified by:

getDependencies in interface BeanProvider

Overrides:

getDependencies in class LifeCycleBeanProvider

Returns:

the dependencies of this bean provider

See Also:

Dependency

getLockID

public Long getLockID()

Returns the ID of the locking transaction. As long as no bean has been created yet, this implementation behaves like the method of the base class. After that it will always return null, because from now on there is no need for synchronization any more.

Specified by:

getLockID in interface BeanProvider

Overrides:

getLockID in class LifeCycleBeanProvider

Returns:

the ID of the locking transaction

shutdown

public void shutdown(DependencyProvider depProvider)

Tells this provider that it is no more needed. This implementation invokes the shutdown handler if a bean was already created.

Specified by:

shutdown in interface BeanProvider

Overrides:

shutdown in class LifeCycleBeanProvider

Parameters:

depProvider - the DependencyProvider