Package org.jgrapes.util

Class PreferencesStore

java.lang.Object

org.jgrapes.core.internal.ComponentVertex

org.jgrapes.core.Component

org.jgrapes.util.ConfigurationStore

org.jgrapes.util.PreferencesStore

All Implemented Interfaces:

Iterable<ComponentType>, Channel, ComponentType, Eligible, Manager

public class PreferencesStore
extends ConfigurationStore

This component provides a store for an application’s configuration backed by the Java Preferences.

Preferences are maps of key value pairs that are associated with a path. A common base path is passed to the component on creation. The application’s configuration information is stored using paths relative to that base path.

The component reads the initial values from the Java Preferences tree denoted by the base path. During application bootstrap, it intercepts the Start event using a handler with priority 999999. When receiving this event, it fires all known preferences values on the channels of the start event as a InitialPreferences event, using a new EventPipeline and waiting for its completion. Then, allows the intercepted Start event to continue.

Components that depend on configuration values define handlers for ConfigurationUpdate events and adapt themselves to the values received. Note that due to the intercepted Start event, the initial preferences values are received before the Start event, so components’ configurations can be rearranged before they actually start doing something.

Besides initially publishing the stored preferences values, the component also listens for ConfigurationUpdate events on its channel and updates the preferences store (may be suppressed).

Nested Class Summary

Nested classes/interfaces inherited from interface org.jgrapes.core.Channel

Channel.Default

Field Summary

Fields inherited from class org.jgrapes.util.ConfigurationStore

NUMBER

Fields inherited from class org.jgrapes.core.Component

logger

Fields inherited from interface org.jgrapes.core.Channel

BROADCAST, SELF

Constructor Summary

Constructors

Constructor	Description
PreferencesStore(Channel componentChannel, Class<?> appClass)	Creates a new component with its channel set to the given channel and a base path derived from the given class.
PreferencesStore(Channel componentChannel, Class<?> appClass, boolean update)	Allows the creation of a “read-only” store.

Method Summary

Modifier and Type	Method	Description
void	onConfigurationUpdate(ConfigurationUpdate event)	Merges and saves configuration updates.
void	onStart(Start event)	Intercepts the Start event and fires a ConfigurationUpdate event.
Optional<Map<String,Object>>	structured(String path)	Return the properties for a given path if they exists as structured data, see ConfigurationStore.structure(Map).
Optional<Map<String,String>>	values(String path)	Return the values for a given path if they exist.

Methods inherited from class org.jgrapes.util.ConfigurationStore

as, asBoolean, asInstant, asNumber, asString, flatten, mergeValue, structure, structure

Methods inherited from class org.jgrapes.core.Component

channel, component, defaultCriterion, isEligibleFor, setName

Methods inherited from class org.jgrapes.core.internal.ComponentVertex

activeEventPipeline, addHandler, attach, channelReplacements, children, componentPath, componentVertex, detach, fire, initComponentsHandlers, iterator, name, newEventPipeline, newEventPipeline, parent, registerAsGenerator, root, toString, unregisterAsGenerator

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Methods inherited from interface org.jgrapes.core.Manager

stream

Constructor Details

PreferencesStore

public PreferencesStore(Channel componentChannel,
 Class<?> appClass)

Creates a new component with its channel set to the given channel and a base path derived from the given class.

Parameters:

componentChannel - the channel

appClass - the application class; the base path is formed by replacing each dot in the class’s package’s full name with a slash, prepending a slash, and appending “/PreferencesStore”.

PreferencesStore

public PreferencesStore(Channel componentChannel,
 Class<?> appClass,
 boolean update)

Allows the creation of a “read-only” store.

Parameters:

componentChannel - the channel

appClass - the application class; the base path is formed by replacing each dot in the class’s package’s full name with a slash, prepending a slash, and appending “/PreferencesStore”.

update - whether to update the store when ConfigurationUpdate events are received

See Also:

• PreferencesStore(Channel, Class)

Method Details

onStart

@Handler(priority=999999,
         channels=Channel.class)
public void onStart(Start event)
             throws BackingStoreException,
InterruptedException

Intercepts the Start event and fires a ConfigurationUpdate event.

Parameters:

event - the event

Throws:

BackingStoreException - the backing store exception

InterruptedException - the interrupted exception

onConfigurationUpdate

@Handler(dynamic=true)
public void onConfigurationUpdate(ConfigurationUpdate event)
                           throws BackingStoreException

Merges and saves configuration updates.

Parameters:

event - the event

Throws:

IOException - Signals that an I/O exception has occurred.

BackingStoreException

values

public Optional<Map<String,String>> values(String path)

Description copied from class: ConfigurationStore

Return the values for a given path if they exist.

This method should only be used in cases where configuration values are needed before the InitialConfiguration event is fired, e.g. while creating the component tree.

Overrides:

values in class ConfigurationStore

Parameters:

path - the path

Returns:

the values, if defined for the given path

structured

public Optional<Map<String,Object>> structured(String path)

Description copied from class: ConfigurationStore

Return the properties for a given path if they exists as structured data, see ConfigurationStore.structure(Map).

Overrides:

structured in class ConfigurationStore

Parameters:

path - the path

Returns:

the values, if defined for the given path