org.sape.carbon.core.config
Class Config

java.lang.Object
  |
  +--org.sape.carbon.core.config.Config

All Implemented Interfaces:

ConfigurationService

public class Config

extends Object

implements ConfigurationService

Config implements a static singleton pattern to provide a single point of access for configuration data. Configuration data in the form of Configuration objects can be accessed from an underlying data store, and written to an underlying data store via Config. The Config is the preferred class for accessing configuration data.

Copyright 2002 Sapient

Since:

carbon 1.0

Version:

$Revision: 1.27 $($Author: dvoet $ / $Date: 2003/12/11 18:43:31 $)

Author:

Mike Redd, January 2002

Field Summary

private ConfigurationService	configService Cached reference to the initial ConfigurationService in the system.
private static Config	INSTANCE Reference to the one and only instance of this class, following the Item 2 in Josh Bloch's "Effective Java".
static String	ROOT_NODE_NAME The name of the root node for use in the fetchNode method

Constructor Summary

private

Config() Private constructor to ensure that others do not instantiate a unique Config object.

Method Summary

void	addNodeListener(String nodeName, ConfigurationEventListener listener) Adds a listener to the specified node.
void	addNodeListener(String nodeName, NodeEventListener listener) Adds a listener to the specified node.
Configuration	createConfiguration(Class configurationType) This method is the primary interface to create new instances of Configuration Objects.
Configuration	fetchConfiguration(String name) Returns a Configuration object that contains all of the configuration data in the ConfigurationDocument located by configurationName.
Node	fetchNode(String nodeName) Traverses the internal node hierachy and returns the named node
Configuration	fetchWritableConfiguration(String name) Returns a Configuration object that contains all of the configuration data in the ConfigurationDocument located by configurationName.
ConfigurationService	getConfigurationService() Provides static access to the Configuration Service.
static Config	getInstance() Accessor to the single instance of Config.
boolean	nodeExists(String nodeName) Returns true if the node exists in the configuration repository and false if it does not exist.
void	storeConfiguration(String name, Configuration config) The storeConfiguration method persists configuration data contained in config to the underlying ConfigurationDocument named by configurationName.

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

private static Config INSTANCE

Reference to the one and only instance of this class, following the Item 2 in Josh Bloch's "Effective Java".

ROOT_NODE_NAME

public static final String ROOT_NODE_NAME

The name of the root node for use in the fetchNode method

configService

private ConfigurationService configService

Cached reference to the initial ConfigurationService in the system.

Constructor Detail

Config

private Config()

Private constructor to ensure that others do not instantiate a unique Config object.

Method Detail

getInstance

public static Config getInstance()

Accessor to the single instance of Config.

Returns:

The single instance of Config.

fetchConfiguration

public Configuration fetchConfiguration(String name)

Description copied from interface: ConfigurationService

Returns a Configuration object that contains all of the configuration data in the ConfigurationDocument located by configurationName.

The returned configuration may be a shared object that is read-only. If it is, the configuration's writable flag is set to false and exceptions will be thrown if an attempt is made to modify the object.

Specified by:

fetchConfiguration in interface ConfigurationService

Parameters:

name - The name of the requested configuration

Returns:

Configuration object that may be used to access discrete configuration data.

See Also:

ConfigurationService.fetchConfiguration(java.lang.String)

fetchWritableConfiguration

public Configuration fetchWritableConfiguration(String name)

Description copied from interface: ConfigurationService

Returns a Configuration object that contains all of the configuration data in the ConfigurationDocument located by configurationName.

The returned configuration is a mutable object and not thread-safe. All access to this object should be in a single threaded or synchronized context. To commit the changes that have been made to this object use the storeConfiguration method.

Specified by:

fetchWritableConfiguration in interface ConfigurationService

Parameters:

name - The name of the requested configuration

Returns:

Configuration object that may be used to access discrete configuration data.

See Also:

ConfigurationService.fetchWritableConfiguration(java.lang.String)

storeConfiguration

public void storeConfiguration(String name,
                               Configuration config)
                        throws ConfigurationStoreException

Description copied from interface: ConfigurationService

The storeConfiguration method persists configuration data contained in config to the underlying ConfigurationDocument named by configurationName. If the ConfigurationDocument does not exist, it is created along with all of its parent Nodes.

Specified by:

storeConfiguration in interface ConfigurationService

Parameters:

name - The name of the Configuration Document where the configuration data should be stored.

config - Configuration data to be persisted to the underlying data store.

Throws:

ConfigurationStoreException - data can not be written to the backing store.

See Also:

ConfigurationService.storeConfiguration(java.lang.String, org.sape.carbon.core.config.Configuration)

createConfiguration

public Configuration createConfiguration(Class configurationType)

Description copied from interface: ConfigurationService

This method is the primary interface to create new instances of Configuration Objects. This method is capable of creating an empty configuration object for an interface that extends the Configuration interface.

Specified by:

createConfiguration in interface ConfigurationService

Parameters:

configurationType - The Class of the configuration type to be created

Returns:

an empty instance of a configuration object implementing the provided class.

See Also:

ConfigurationService.createConfiguration(java.lang.Class)

fetchNode

public Node fetchNode(String nodeName)
               throws NodeNotFoundException

Description copied from interface: ConfigurationService

Traverses the internal node hierachy and returns the named node

Specified by:

fetchNode in interface ConfigurationService

Parameters:

nodeName - the '/' delimeted path to the node

Returns:

The node specifed by nodeName.

Throws:

NodeNotFoundException - when the cannot be found.

See Also:

ConfigurationService.fetchNode(java.lang.String)

nodeExists

public boolean nodeExists(String nodeName)

Description copied from interface: ConfigurationService

Returns true if the node exists in the configuration repository and false if it does not exist. This is meant to be an alternative to getting Node not found exceptions when you have nodes that aren't required.

Specified by:

nodeExists in interface ConfigurationService

Parameters:

nodeName - the '/' delimeted path to the node

Returns:

if the node exists

See Also:

ConfigurationService.nodeExists(java.lang.String)

addNodeListener

public void addNodeListener(String nodeName,
                            NodeEventListener listener)
                     throws NodeNotFoundException

Deprecated. use void addNodeListener(String nodeName, ConfigurationEventListener listener) instead

Description copied from interface: ConfigurationService

Adds a listener to the specified node.

Specified by:

addNodeListener in interface ConfigurationService

Parameters:

nodeName - the '/' delimeted path to the node

listener - the object that will be notified of NodeEvents

Throws:

NodeNotFoundException - if nodeName does not exist

See Also:

ConfigurationService.addNodeListener(String, NodeEventListener)

addNodeListener

public void addNodeListener(String nodeName,
                            ConfigurationEventListener listener)
                     throws NodeNotFoundException

Description copied from interface: ConfigurationService

Adds a listener to the specified node.

Specified by:

addNodeListener in interface ConfigurationService

Parameters:

nodeName - the '/' delimeted path to the node

listener - the object that will be notified of NodeEvents

Throws:

NodeNotFoundException - if nodeName does not exist

See Also:

ConfigurationService.addNodeListener(String, ConfigurationEventListener)

getConfigurationService

public ConfigurationService getConfigurationService()

Provides static access to the Configuration Service.

Returns:

returns the configuration service used by default in the system.