Package org.apache.turbine.services

Class BaseInitableBroker

java.lang.Object

org.apache.turbine.services.BaseInitableBroker

All Implemented Interfaces:

InitableBroker

public abstract class BaseInitableBroker
extends Object
implements InitableBroker

A generic implementation of InitableBroker. Functionality provided by the broker includes:

• Maintaining single instance of each Initable in the system.
• Early initialization of Initables during system startup.
• Late initialization of Initables before they are used.
• Providing instances of Initables to requesting parties.
• Maintaining dependencies between Initables during early initialization phases, including circular dependencies detection.

Version:

$Id$

Author:

Kevin Burton, Rafal Krzewski, Henning P. Schmiedehausen

Field Summary

Fields

Modifier and Type	Field	Description
protected Hashtable<String,Initable>	initables	A repository of Initable instances.
protected Stack<String>	stack	Names of classes being early-initialized are pushed onto this stack.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	BaseInitableBroker()	Default constructor of InitableBroker.

Method Summary

Modifier and Type	Method	Description
Initable	getInitable(String className)	Provides an instance of Initable class ready to work.
protected Initable	getInitableInstance(String className)	Retrieves an instance of an Initable from the repository.
void	initClass(String className, Object data)	Performs early initialization of an Initable class.
void	shutdownClass(String className)	Shuts down an Initable.

Methods inherited from class java.lang.Object

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

Field Detail

initables

protected Hashtable<String,Initable> initables

A repository of Initable instances.

stack

protected Stack<String> stack

Names of classes being early-initialized are pushed onto this stack. A name appearing twice indicates a circular dependency chain.

Constructor Detail

BaseInitableBroker

protected BaseInitableBroker()

Default constructor of InitableBroker. This constructor does nothing. Your brokers should be singletons, therefore their constructors should be private. They should also have public YourBroker getInstance() methods.

Method Detail

initClass

public void initClass(String className,
                      Object data)
               throws InitializationException

Performs early initialization of an Initable class.

Specified by:

initClass in interface InitableBroker

Parameters:

className - The name of the class to be initialized.

data - An Object to be used for initialization activities.

Throws:

InitializationException - Initialization was not successful.

shutdownClass

public void shutdownClass(String className)

Shuts down an Initable. This method is used to release resources allocated by an Initable, and return it to its initial (uninitialized) state.

Specified by:

shutdownClass in interface InitableBroker

Parameters:

className - The name of the class to be uninitialized.

getInitable

public Initable getInitable(String className)
                     throws InstantiationException

Provides an instance of Initable class ready to work. If the requested class couldn't be instantiated or initialized, an InstantiationException will be thrown. You needn't handle this exception in your code, since it indicates fatal misconfiguration of the system.

Specified by:

getInitable in interface InitableBroker

Parameters:

className - The name of the Initable requested.

Returns:

An instance of the requested Initable.

Throws:

InstantiationException - if there was a problem during instantiation or initialization of the Initable.

getInitableInstance

protected Initable getInitableInstance(String className)
                                throws InstantiationException

Retrieves an instance of an Initable from the repository. If the requested class is not present in the repository, it is instantiated and passed a reference to the broker, saved and then returned.

Parameters:

className - The name of the class to be instantiated.

Returns:

an instance of the requested class

Throws:

InstantiationException - if the requested class can't be instantiated.