tools.gsf.config

Class DefaultFactoryProducer

java.lang.Object

tools.gsf.config.DefaultFactoryProducer

All Implemented Interfaces:

FactoryProducer

public class DefaultFactoryProducer
extends Object
implements FactoryProducer

Default factory producer class that creates factory classes for the scopes specified.

Factory classes will be looked up in a configuration file called CONFIG_FILE. The format of the file is as follows: blank lines are allowed (and ignored); comments are allowed (and ignored). The comment indicator is (#).

Each functional line of the configuration file has two parts, the factory class name, and the scope class name. For example: scope.class.name : factory.class.name

Each factory class name must have a two-argument constructor. The first argument is the scope class, the very same class that is passed into the getFactory(Object) method. The second argument is the optional delegate factory that the specified factory will defer to if it is not able to locate the specified object. (If no parent is specified, no delegation will occur).

Only one factory class per scope may be defined. If more than one is found, a configuration error will be thrown.

By default, DefaultFactoryProducer knows how to get access to the ServletContext from within the ICS object, and so a factory corresponding to the ServletContext scope will be used as the delegate for the ICS scoped factory. Users may override either of these two and the relationship will be preserved.

Conversely, this factory producer does not know the relationship between any custom scope and the two it knows about, and so it is unable to automatically wire delegation between factories involving custom scopes. To do this, it is necessary to extend this class (or replace it).

Also, this factory producer does not know how to cache factories with custom scopes, so new versions will be created whenever one is requested. For the known scopes, caching is built-in.

Since:

2016-08-05

Author:

Tony Field

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	CONFIG_FILE The configuration file(s) that this class will read while looking for information about which factories to use
protected static String	ICS_CONTEXT_BACKED_FACTORY The ics object pool key for the ics-backed factory.
protected static String	SERVLET_CONTEXT_BACKED_FACTORY The servlet context attribute key for the servletContext-backed factory.

Constructor Summary

Constructors

Constructor and Description
DefaultFactoryProducer() Creates a new factory producer.

Method Summary

Modifier and Type	Method and Description
protected Factory	createFactory(COM.FutureTense.Interfaces.ICS ics) Create a new instance of the ics-backed factory.
protected Factory	createFactory(Object customScope) Create a custom-scoped factory.
protected Factory	createFactory(javax.servlet.ServletContext servletContext) Create a new instance of the servletContext-backed factory.
protected static Map<Class,Constructor<Factory>>	getConstructorMap(Map<Class,Class> config) Converts the map of classes to a map containing factory constructors as the value.
protected Factory	getFactory(COM.FutureTense.Interfaces.ICS ics) Get the ics-backed factory.
Factory	getFactory(Object scope) Get the factory configured for the scope specified.
protected Factory	getFactory(javax.servlet.ServletContext servletContext) Get the servletContext-backed factory.
protected static Map<Class,Class>	lookupConfiguration(ClassLoader classLoader) Look up the configuration for the FactoryProducer by reading the CONFIG_FILEs found in the specified ClassLoader's classpath.

Methods inherited from class java.lang.Object

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

Field Detail

CONFIG_FILE

protected static final String CONFIG_FILE

The configuration file(s) that this class will read while looking for information about which factories to use

See Also:

Constant Field Values

ICS_CONTEXT_BACKED_FACTORY

protected static final String ICS_CONTEXT_BACKED_FACTORY

The ics object pool key for the ics-backed factory.

See Also:

Constant Field Values

SERVLET_CONTEXT_BACKED_FACTORY

protected static final String SERVLET_CONTEXT_BACKED_FACTORY

The servlet context attribute key for the servletContext-backed factory.

See Also:

Constant Field Values

Constructor Detail

DefaultFactoryProducer

public DefaultFactoryProducer()

Creates a new factory producer. This constructor pre-reads the configuration files and validates that constructors exist for the scope specified.

If no factory is configured for ICS or ServletContext, a default is provided.

Method Detail

getFactory

public Factory getFactory(Object scope)

Description copied from interface: FactoryProducer

Get the factory configured for the scope specified. If no factory is present for the specified scope, an IllegalArgumentException is thrown.

Specified by:

getFactory in interface FactoryProducer

Parameters:

scope - the scope

Returns:

the factory

createFactory

protected Factory createFactory(Object customScope)

Create a custom-scoped factory. Note that there is no caching support for a custom scope (because this class does not know enough about the scope to know how to cache against it). Subclasses can override this method and create their own internal cache.

Parameters:

customScope - custom scope

Returns:

the factory

getFactory

protected Factory getFactory(COM.FutureTense.Interfaces.ICS ics)

Get the ics-backed factory. Once created, the factory is cached on the ICS object pool using ICS_CONTEXT_BACKED_FACTORY as the key.

Parameters:

ics - ics context

Returns:

the factory, never null

createFactory

protected Factory createFactory(COM.FutureTense.Interfaces.ICS ics)

Create a new instance of the ics-backed factory.

This implementation uses the constructor configured in the CONFIG_FILE. It also uses ICS to locate the ServletContext, and then gets the servletContext-backed factory which it will use as a delegate for the ics-backed factory.

Parameters:

ics - the ics context

Returns:

the factory

getFactory

protected Factory getFactory(javax.servlet.ServletContext servletContext)

Get the servletContext-backed factory. Once created, the factory is cached on the servlet context pool using SERVLET_CONTEXT_BACKED_FACTORY as the key.

Parameters:

servletContext - the servlet context

Returns:

the factory, never null

createFactory

protected Factory createFactory(javax.servlet.ServletContext servletContext)

Create a new instance of the servletContext-backed factory.

This implementation uses the constructor configured in the CONFIG_FILE.

Parameters:

servletContext - the servlet context

Returns:

the factory, never null

lookupConfiguration

protected static Map<Class,Class> lookupConfiguration(ClassLoader classLoader)

Look up the configuration for the FactoryProducer by reading the CONFIG_FILEs found in the specified ClassLoader's classpath. The configuration file format is described above.

Parameters:

classLoader - the classloader to do the looking

Returns:

map containing the classes from the config file

Throws:

IllegalStateException - if the config file format is invalid, if more than one configuration setting is found for a given scope, or if the config file points to classes that are not found.

getConstructorMap

protected static Map<Class,Constructor<Factory>> getConstructorMap(Map<Class,Class> config)

Converts the map of classes to a map containing factory constructors as the value.

This class will look for a constructor with the signature described above, and will fail if one is not found.

Parameters:

config - the mapping between scope and factory constructors to be used to create the factories

Returns:

a map containing factory constructors for each scope. Never null

Throws:

IllegalStateException - if no constructor can be found with the appropriate signature, or if the class specified does not implement the Factory interface.