org.apache.commons.configuration
Class SubnodeConfiguration

java.lang.Object
  org.apache.commons.configuration.event.EventSource
      org.apache.commons.configuration.AbstractConfiguration
          org.apache.commons.configuration.HierarchicalConfiguration
              org.apache.commons.configuration.SubnodeConfiguration

All Implemented Interfaces:

Cloneable, Configuration, Serializable

public class SubnodeConfiguration

extends HierarchicalConfiguration

A specialized hierarchical configuration class that wraps a single node of its parent configuration.

Configurations of this type are initialized with a parent configuration and a configuration node of this configuration. This node becomes the root node of the subnode configuration. All property accessor methods are evaluated relative to this root node. A good use case for a SubnodeConfiguration is when multiple properties from a specific sub tree of the whole configuration need to be accessed. Then a SubnodeConfiguration can be created with the parent node of the affected sub tree as root node. This allows for simpler property keys and is also more efficient.

A subnode configuration and its parent configuration operate on the same hierarchy of configuration nodes. So if modifications are performed at the subnode configuration, these changes are immideately visible in the parent configuration. Analogously will updates of the parent configuration affect the subnode configuration if the sub tree spanned by the subnode configuration's root node is involved.

When a subnode configuration is created, it inherits the settings of its parent configuration, e.g. some flags like the throwExceptionOnMissing flag or the settings for handling list delimiters) or the expression engine. If these settings are changed later in either the subnode or the parent configuration, the changes are not visible for each other. So you could create a subnode configuration, change its expression engine without affecting the parent configuration.

From its purpose this class is quite similar to SubsetConfiguration. The difference is that a subset configuration of a hierarchical configuration may combine multiple configuration nodes from different sub trees of the configuration, while all nodes in a subnode configuration belong to the same sub tree. If an application can live with this limitation, it is recommended to use this class instead of SubsetConfiguration because creating a subset configuration is more expensive than creating a subnode configuration.

Since:

1.3

Version:

$Id: SubnodeConfiguration.java 439648 2006-09-02 20:42:10Z oheger $

Author:

Oliver Heger

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class org.apache.commons.configuration.HierarchicalConfiguration

HierarchicalConfiguration.BuilderVisitor, HierarchicalConfiguration.CloneVisitor, HierarchicalConfiguration.DefinedKeysVisitor, HierarchicalConfiguration.DefinedVisitor, HierarchicalConfiguration.Node, HierarchicalConfiguration.NodeVisitor

Field Summary

Fields inherited from class org.apache.commons.configuration.HierarchicalConfiguration

EVENT_ADD_NODES, EVENT_CLEAR_TREE

Fields inherited from class org.apache.commons.configuration.AbstractConfiguration

END_TOKEN, EVENT_ADD_PROPERTY, EVENT_CLEAR, EVENT_CLEAR_PROPERTY, EVENT_SET_PROPERTY, START_TOKEN

Constructor Summary

SubnodeConfiguration(HierarchicalConfiguration parent, ConfigurationNode root)
Creates a new instance of SubnodeConfiguration and initializes it with the parent configuration and the new root node.

Method Summary

protected HierarchicalConfiguration.Node	createNode(String name) Creates a new node.
protected SubnodeConfiguration	createSubnodeConfiguration(ConfigurationNode node) Returns a hierarchical configuration object for the given sub node.
HierarchicalConfiguration	getParent() Returns the parent configuration of this subnode configuration.
protected void	initFromParent(HierarchicalConfiguration parentConfig) Initializes this subnode configuration from the given parent configuration.
protected Object	interpolate(Object value) Performs interpolation.

Methods inherited from class org.apache.commons.configuration.HierarchicalConfiguration

addNodes, addPropertyDirect, clearNode, clearNode, clearProperty, clearTree, clone, configurationAt, configurationsAt, containsKey, createAddPath, fetchAddNode, fetchNodeList, findLastPathNode, findPropertyNodes, getDefaultExpressionEngine, getExpressionEngine, getKeys, getKeys, getMaxIndex, getProperty, getRoot, getRootNode, isEmpty, nodeDefined, nodeDefined, removeNode, removeNode, setDefaultExpressionEngine, setExpressionEngine, setProperty, setRoot, setRootNode, subset

Methods inherited from class org.apache.commons.configuration.AbstractConfiguration

addProperty, clear, clearPropertyDirect, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDefaultListDelimiter, getDelimiter, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getList, getList, getListDelimiter, getLong, getLong, getLong, getProperties, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, interpolate, interpolateHelper, isDelimiterParsingDisabled, isThrowExceptionOnMissing, resolveContainerStore, setDefaultListDelimiter, setDelimiter, setDelimiterParsingDisabled, setListDelimiter, setThrowExceptionOnMissing

Methods inherited from class org.apache.commons.configuration.event.EventSource

addConfigurationListener, clearConfigurationListeners, createEvent, fireEvent, getConfigurationListeners, isDetailEvents, removeConfigurationListener, setDetailEvents

Methods inherited from class java.lang.Object

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

Constructor Detail

SubnodeConfiguration

public SubnodeConfiguration(HierarchicalConfiguration parent,
                            ConfigurationNode root)

Creates a new instance of SubnodeConfiguration and initializes it with the parent configuration and the new root node.

Parameters:

parent - the parent configuration

root - the root node of this subnode configuration

Method Detail

getParent

public HierarchicalConfiguration getParent()

Returns the parent configuration of this subnode configuration.

Returns:

the parent configuration

createSubnodeConfiguration

protected SubnodeConfiguration createSubnodeConfiguration(ConfigurationNode node)

Returns a hierarchical configuration object for the given sub node. This implementation will ensure that the returned SubnodeConfiguration object will have the same parent than this object.

Overrides:

createSubnodeConfiguration in class HierarchicalConfiguration

Parameters:

node - the sub node, for which the configuration is to be created

Returns:

a hierarchical configuration for this sub node

createNode

protected HierarchicalConfiguration.Node createNode(String name)

Creates a new node. This task is delegated to the parent.

Overrides:

createNode in class HierarchicalConfiguration

Parameters:

name - the node's name

Returns:

the new node

initFromParent

protected void initFromParent(HierarchicalConfiguration parentConfig)

Initializes this subnode configuration from the given parent configuration. This method is called by the constructor. It will copy many settings from the parent.

Parameters:

parentConfig - the parent configuration

interpolate

protected Object interpolate(Object value)

Performs interpolation. This implementation will ask the parent configuration to perform the interpolation so that variables can be evaluated in the global context.

Overrides:

interpolate in class AbstractConfiguration

Parameters:

value - the value to be interpolated

Returns:

returns the value with variables substituted