org.apache.commons.configuration

Class SubsetConfiguration

java.lang.Object

org.apache.commons.configuration.event.EventSource

org.apache.commons.configuration.AbstractConfiguration

org.apache.commons.configuration.SubsetConfiguration

All Implemented Interfaces:

Configuration

public class SubsetConfiguration
extends AbstractConfiguration

A subset of another configuration. The new Configuration object contains every key from the parent Configuration that starts with prefix. The prefix is removed from the keys in the subset.

It is usually not necessary to use this class directly. Instead the Configuration.subset(String) method should be used, which will return a correctly initialized instance.

Version:

$Id: SubsetConfiguration.java 1210202 2011-12-04 20:30:46Z oheger $

Author:

Emmanuel Bourg

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	delimiter The prefix delimiter
protected Configuration	parent The parent configuration.
protected java.lang.String	prefix The prefix used to select the properties.

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

END_TOKEN, EVENT_ADD_PROPERTY, EVENT_CLEAR, EVENT_CLEAR_PROPERTY, EVENT_READ_PROPERTY, EVENT_SET_PROPERTY, START_TOKEN

Constructor Summary

Constructors

Constructor and Description
SubsetConfiguration(Configuration parent, java.lang.String prefix) Create a subset of the specified configuration
SubsetConfiguration(Configuration parent, java.lang.String prefix, java.lang.String delimiter) Create a subset of the specified configuration

Method Summary

Modifier and Type	Method and Description
void	addPropertyDirect(java.lang.String key, java.lang.Object value) Adds a key/value pair to the Configuration.
protected void	clearPropertyDirect(java.lang.String key) Removes the specified property from this configuration.
boolean	containsKey(java.lang.String key) Check if the configuration contains the specified key.
protected java.lang.String	getChildKey(java.lang.String key) Return the key in the subset configuration associated to the specified key in the parent configuration.
java.util.Iterator<java.lang.String>	getKeys() Get the list of the keys contained in the configuration.
java.util.Iterator<java.lang.String>	getKeys(java.lang.String prefix) Get the list of the keys contained in the configuration that match the specified prefix.
char	getListDelimiter() Returns the list delimiter.
Configuration	getParent() Return the parent configuration for this subset.
protected java.lang.String	getParentKey(java.lang.String key) Return the key in the parent configuration associated to the specified key in this subset.
java.lang.String	getPrefix() Return the prefix used to select the properties in the parent configuration.
java.lang.Object	getProperty(java.lang.String key) Gets a property from the configuration.
protected java.lang.Object	interpolate(java.lang.Object base) Returns the interpolated value.
protected java.lang.String	interpolate(java.lang.String base) interpolate key names to handle ${key} stuff
boolean	isDelimiterParsingDisabled() Returns a flag whether string properties should be checked for list delimiter characters.
boolean	isEmpty() Check if the configuration is empty.
boolean	isThrowExceptionOnMissing() Returns true if missing values throw Exceptions.
void	setDelimiterParsingDisabled(boolean delimiterParsingDisabled) Sets a flag whether list parsing is disabled.
void	setListDelimiter(char delim) Sets the list delimiter.
void	setPrefix(java.lang.String prefix) Set the prefix used to select the properties in the parent configuration.
void	setThrowExceptionOnMissing(boolean throwExceptionOnMissing) Allows to set the throwExceptionOnMissing flag.
Configuration	subset(java.lang.String prefix) Return a decorator Configuration containing every key from the current Configuration that starts with the specified prefix.

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

addErrorLogListener, addProperty, append, clear, clearProperty, copy, createInterpolator, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDefaultListDelimiter, getDelimiter, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getInterpolator, getList, getList, getLogger, getLong, getLong, getLong, getProperties, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, getSubstitutor, interpolatedConfiguration, interpolateHelper, isScalarValue, resolveContainerStore, setDefaultListDelimiter, setDelimiter, setLogger, setProperty

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

addConfigurationListener, addErrorListener, clearConfigurationListeners, clearErrorListeners, clone, createErrorEvent, createEvent, fireError, fireEvent, getConfigurationListeners, getErrorListeners, isDetailEvents, removeConfigurationListener, removeErrorListener, setDetailEvents

Methods inherited from class java.lang.Object

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

Field Detail

parent

protected Configuration parent

The parent configuration.

prefix

protected java.lang.String prefix

The prefix used to select the properties.

delimiter

protected java.lang.String delimiter

The prefix delimiter

Constructor Detail

SubsetConfiguration

public SubsetConfiguration(Configuration parent,
                           java.lang.String prefix)

Create a subset of the specified configuration

Parameters:

parent - The parent configuration

prefix - The prefix used to select the properties

SubsetConfiguration

public SubsetConfiguration(Configuration parent,
                           java.lang.String prefix,
                           java.lang.String delimiter)

Create a subset of the specified configuration

Parameters:

parent - The parent configuration

prefix - The prefix used to select the properties

delimiter - The prefix delimiter

Method Detail

getParentKey

protected java.lang.String getParentKey(java.lang.String key)

Return the key in the parent configuration associated to the specified key in this subset.

Parameters:

key - The key in the subset.

Returns:

the key as to be used by the parent

getChildKey

protected java.lang.String getChildKey(java.lang.String key)

Return the key in the subset configuration associated to the specified key in the parent configuration.

Parameters:

key - The key in the parent configuration.

Returns:

the key in the context of this subset configuration

getParent

public Configuration getParent()

Return the parent configuration for this subset.

Returns:

the parent configuration

getPrefix

public java.lang.String getPrefix()

Return the prefix used to select the properties in the parent configuration.

Returns:

the prefix used by this subset

setPrefix

public void setPrefix(java.lang.String prefix)

Set the prefix used to select the properties in the parent configuration.

Parameters:

prefix - the prefix

subset

public Configuration subset(java.lang.String prefix)

Description copied from interface: Configuration

Return a decorator Configuration containing every key from the current Configuration that starts with the specified prefix. The prefix is removed from the keys in the subset. For example, if the configuration contains the following properties:

    prefix.number = 1
    prefix.string = Apache
    prefixed.foo = bar
    prefix = Jakarta

the Configuration returned by subset("prefix") will contain the properties:

    number = 1
    string = Apache
    = Jakarta

(The key for the value "Jakarta" is an empty string)

Since the subset is a decorator and not a modified copy of the initial Configuration, any change made to the subset is available to the Configuration, and reciprocally.

Specified by:

subset in interface Configuration

Overrides:

subset in class AbstractConfiguration

Parameters:

prefix - The prefix used to select the properties.

Returns:

a subset configuration

See Also:

SubsetConfiguration

isEmpty

public boolean isEmpty()

Description copied from interface: Configuration

Check if the configuration is empty.

Returns:

true if the configuration contains no property, false otherwise.

containsKey

public boolean containsKey(java.lang.String key)

Description copied from interface: Configuration

Check if the configuration contains the specified key.

Parameters:

key - the key whose presence in this configuration is to be tested

Returns:

true if the configuration contains a value for this key, false otherwise

addPropertyDirect

public void addPropertyDirect(java.lang.String key,
                              java.lang.Object value)

Description copied from class: AbstractConfiguration

Adds a key/value pair to the Configuration. Override this method to provide write access to underlying Configuration store.

Specified by:

addPropertyDirect in class AbstractConfiguration

Parameters:

key - key to use for mapping

value - object to store

clearPropertyDirect

protected void clearPropertyDirect(java.lang.String key)

Description copied from class: AbstractConfiguration

Removes the specified property from this configuration. This method is called by clearProperty() after it has done some preparations. It should be overridden in sub classes. This base implementation is just left empty.

Overrides:

clearPropertyDirect in class AbstractConfiguration

Parameters:

key - the key to be removed

getProperty

public java.lang.Object getProperty(java.lang.String key)

Description copied from interface: Configuration

Gets a property from the configuration. This is the most basic get method for retrieving values of properties. In a typical implementation of the Configuration interface the other get methods (that return specific data types) will internally make use of this method. On this level variable substitution is not yet performed. The returned object is an internal representation of the property value for the passed in key. It is owned by the Configuration object. So a caller should not modify this object. It cannot be guaranteed that this object will stay constant over time (i.e. further update operations on the configuration may change its internal state).

Parameters:

key - property to retrieve

Returns:

the value to which this configuration maps the specified key, or null if the configuration contains no mapping for this key.

getKeys

public java.util.Iterator<java.lang.String> getKeys(java.lang.String prefix)

Description copied from class: AbstractConfiguration

Get the list of the keys contained in the configuration that match the specified prefix. For instance, if the configuration contains the following keys:
db.user, db.pwd, db.url, window.xpos, window.ypos,
an invocation of getKeys("db");
will return the keys below:
db.user, db.pwd, db.url.
Note that the prefix itself is included in the result set if there is a matching key. The exact behavior - how the prefix is actually interpreted - depends on a concrete implementation. This implementation returns keys that either match the prefix or start with the prefix followed by a dot ('.'). So the call getKeys("db"); will find the keys db, db.user, or db.password, but not the key dbdriver.

Specified by:

getKeys in interface Configuration

Overrides:

getKeys in class AbstractConfiguration

Parameters:

prefix - The prefix to test against.

Returns:

An Iterator of keys that match the prefix.

See Also:

Configuration.getKeys()

getKeys

public java.util.Iterator<java.lang.String> getKeys()

Description copied from interface: Configuration

Get the list of the keys contained in the configuration. The returned iterator can be used to obtain all defined keys. Note that the exact behavior of the iterator's remove() method is specific to a concrete implementation. It may remove the corresponding property from the configuration, but this is not guaranteed. In any case it is no replacement for calling Configuration.clearProperty(String) for this property. So it is highly recommended to avoid using the iterator's remove() method.

Returns:

An Iterator.

interpolate

protected java.lang.Object interpolate(java.lang.Object base)

Description copied from class: AbstractConfiguration

Returns the interpolated value. Non String values are returned without change.

Overrides:

interpolate in class AbstractConfiguration

Parameters:

base - the value to interpolate

Returns:

returns the value with variables substituted

interpolate

protected java.lang.String interpolate(java.lang.String base)

Description copied from class: AbstractConfiguration

interpolate key names to handle ${key} stuff

Overrides:

interpolate in class AbstractConfiguration

Parameters:

base - string to interpolate

Returns:

returns the key name with the ${key} substituted

setThrowExceptionOnMissing

public void setThrowExceptionOnMissing(boolean throwExceptionOnMissing)

Allows to set the throwExceptionOnMissing flag. This flag controls the behavior of property getter methods that return objects if the requested property is missing. If the flag is set to false (which is the default value), these methods will return null. If set to true, they will throw a NoSuchElementException exception. Note that getter methods for primitive data types are not affected by this flag. Change the behavior of the parent configuration if it supports this feature.

Overrides:

setThrowExceptionOnMissing in class AbstractConfiguration

Parameters:

throwExceptionOnMissing - The new value for the property

isThrowExceptionOnMissing

public boolean isThrowExceptionOnMissing()

Returns true if missing values throw Exceptions. The subset inherits this feature from its parent if it supports this feature.

Overrides:

isThrowExceptionOnMissing in class AbstractConfiguration

Returns:

true if missing values throw Exceptions

getListDelimiter

public char getListDelimiter()

Returns the list delimiter. This property will be fetched from the parent configuration if supported.

Overrides:

getListDelimiter in class AbstractConfiguration

Returns:

the list delimiter

Since:

1.4

setListDelimiter

public void setListDelimiter(char delim)

Sets the list delimiter. If the parent configuration supports this feature, the delimiter will be set at the parent.

Overrides:

setListDelimiter in class AbstractConfiguration

Parameters:

delim - the new list delimiter

Since:

1.4

isDelimiterParsingDisabled

public boolean isDelimiterParsingDisabled()

Returns a flag whether string properties should be checked for list delimiter characters. This implementation ensures that this flag is kept in sync with the parent configuration if this object supports this feature.

Overrides:

isDelimiterParsingDisabled in class AbstractConfiguration

Returns:

the delimiter parsing disabled flag

Since:

1.4

setDelimiterParsingDisabled

public void setDelimiterParsingDisabled(boolean delimiterParsingDisabled)

Sets a flag whether list parsing is disabled. This implementation will also set the flag at the parent configuration if this object supports this feature.

Overrides:

setDelimiterParsingDisabled in class AbstractConfiguration

Parameters:

delimiterParsingDisabled - the delimiter parsing disabled flag

Since:

1.4