org.apache.commons.configuration

Class EnvironmentConfiguration

java.lang.Object

org.apache.commons.configuration.event.EventSource

org.apache.commons.configuration.AbstractConfiguration

org.apache.commons.configuration.EnvironmentConfiguration

All Implemented Interfaces:

Configuration

public class EnvironmentConfiguration
extends AbstractConfiguration

A Configuration implementation that reads the platform specific environment variables. On pre java5 JRE it uses Ant Execute task to read the environment. (in this case ant must be present in classpath). On java >= 5 JRE it uses java.lang.System#getenv() and ant is not required.

This configuration implementation is read-only. It allows read access to the defined OS environment variables, but their values cannot be changed.

Usage of this class is easy: After an instance has been created the get methods provided by the Configuration interface can be used for querying environment variables, e.g.:

 Configuration envConfig = new EnvironmentConfiguration();
 System.out.println("JAVA_HOME=" + envConfig.getString("JAVA_HOME");
 

Since:

1.5

Author:

Nicolas De Loof

See Also:

org.apache.tools.ant.taskdefs.Execute#getProcEnvironment()

Field Summary

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
EnvironmentConfiguration() Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addPropertyDirect(String key, Object value) Adds a property to this configuration.
void	clear() Removes all properties from this configuration.
void	clearProperty(String key) Removes a property from this configuration.
boolean	containsKey(String key) Check if the configuration contains the specified key.
Iterator	getKeys() Get the list of the keys contained in the configuration.
Object	getProperty(String key) Gets a property from the configuration.
boolean	isEmpty() Check if the configuration is empty.

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

addErrorLogListener, addProperty, append, clearPropertyDirect, copy, createInterpolator, getBigDecimal, getBigDecimal, getBigInteger, getBigInteger, getBoolean, getBoolean, getBoolean, getByte, getByte, getByte, getDefaultListDelimiter, getDelimiter, getDouble, getDouble, getDouble, getFloat, getFloat, getFloat, getInt, getInt, getInteger, getInterpolator, getKeys, getList, getList, getListDelimiter, getLogger, getLong, getLong, getLong, getProperties, getProperties, getShort, getShort, getShort, getString, getString, getStringArray, getSubstitutor, interpolate, interpolate, interpolatedConfiguration, interpolateHelper, isDelimiterParsingDisabled, isThrowExceptionOnMissing, resolveContainerStore, setDefaultListDelimiter, setDelimiter, setDelimiterParsingDisabled, setListDelimiter, setLogger, setProperty, setThrowExceptionOnMissing, subset

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

Constructor Detail

EnvironmentConfiguration

public EnvironmentConfiguration()

Constructor.

Method Detail

addPropertyDirect

protected void addPropertyDirect(String key,
                     Object value)

Adds a property to this configuration. Because this configuration is read-only, this operation is not allowed and will cause an exception.

Specified by:

addPropertyDirect in class AbstractConfiguration

Parameters:

key - the key of the property to be added

value - the property value

containsKey

public boolean containsKey(String key)

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

See Also:

Configuration.containsKey(java.lang.String)

getKeys

public Iterator getKeys()

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.

See Also:

Configuration.getKeys()

getProperty

public Object getProperty(String key)

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.

See Also:

Configuration.getProperty(java.lang.String)

isEmpty

public boolean isEmpty()

Check if the configuration is empty.

Returns:

true if the configuration contains no property, false otherwise.

See Also:

Configuration.isEmpty()

clearProperty

public void clearProperty(String key)

Removes a property from this configuration. Because this configuration is read-only, this operation is not allowed and will cause an exception.

Specified by:

clearProperty in interface Configuration

Overrides:

clearProperty in class AbstractConfiguration

Parameters:

key - the key of the property to be removed

clear

public void clear()

Removes all properties from this configuration. Because this configuration is read-only, this operation is not allowed and will cause an exception.

Specified by:

clear in interface Configuration

Overrides:

clear in class AbstractConfiguration