org.apache.commons.configuration.reloading

Class FileChangedReloadingStrategy

java.lang.Object

org.apache.commons.configuration.reloading.FileChangedReloadingStrategy

All Implemented Interfaces:

ReloadingStrategy

public class FileChangedReloadingStrategy
extends Object
implements ReloadingStrategy

A reloading strategy that will reload the configuration every time its underlying file is changed.

This reloading strategy does not actively monitor a configuration file, but is triggered by its associated configuration whenever properties are accessed. It then checks the configuration file's last modification date and causes a reload if this has changed.

To avoid permanent disc access on successive property lookups a refresh delay can be specified. This has the effect that the configuration file's last modification date is only checked once in this delay period. The default value for this refresh delay is 5 seconds.

This strategy only works with FileConfiguration instances.

Since:

1.1

Version:

$Revision$, $Date$

Author:

Emmanuel Bourg

Field Summary

Fields

Modifier and Type	Field and Description
protected FileConfiguration	configuration Stores a reference to the configuration to be monitored.
protected long	lastChecked The last time the file was checked for changes.
protected long	lastModified The last time the configuration file was modified.
protected long	refreshDelay The minimum delay in milliseconds between checks.

Constructor Summary

Constructors

Constructor and Description
FileChangedReloadingStrategy()

Method Summary

Methods

Modifier and Type	Method and Description
protected File	getFile() Returns the file that is monitored by this strategy.
long	getRefreshDelay() Return the minimal time in milliseconds between two reloadings.
protected boolean	hasChanged() Check if the configuration has changed since the last time it was loaded.
void	init() Initialize the strategy.
void	reloadingPerformed() Notify the strategy that the file has been reloaded.
boolean	reloadingRequired() Tell if the evaluation of the strategy requires to reload the configuration.
void	setConfiguration(FileConfiguration configuration) Set the configuration managed by this strategy.
void	setRefreshDelay(long refreshDelay) Set the minimal time between two reloadings.
protected void	updateLastModified() Update the last modified time.

Methods inherited from class java.lang.Object

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

Field Detail

configuration

protected FileConfiguration configuration

Stores a reference to the configuration to be monitored.

lastModified

protected long lastModified

The last time the configuration file was modified.

lastChecked

protected long lastChecked

The last time the file was checked for changes.

refreshDelay

protected long refreshDelay

The minimum delay in milliseconds between checks.

Constructor Detail

FileChangedReloadingStrategy

public FileChangedReloadingStrategy()

Method Detail

setConfiguration

public void setConfiguration(FileConfiguration configuration)

Description copied from interface: ReloadingStrategy

Set the configuration managed by this strategy.

Specified by:

setConfiguration in interface ReloadingStrategy

Parameters:

configuration - the configuration to monitor

init

public void init()

Description copied from interface: ReloadingStrategy

Initialize the strategy.

Specified by:

init in interface ReloadingStrategy

reloadingRequired

public boolean reloadingRequired()

Description copied from interface: ReloadingStrategy

Tell if the evaluation of the strategy requires to reload the configuration.

Specified by:

reloadingRequired in interface ReloadingStrategy

Returns:

a flag whether a reload should be performed

reloadingPerformed

public void reloadingPerformed()

Description copied from interface: ReloadingStrategy

Notify the strategy that the file has been reloaded.

Specified by:

reloadingPerformed in interface ReloadingStrategy

getRefreshDelay

public long getRefreshDelay()

Return the minimal time in milliseconds between two reloadings.

Returns:

the refresh delay (in milliseconds)

setRefreshDelay

public void setRefreshDelay(long refreshDelay)

Set the minimal time between two reloadings.

Parameters:

refreshDelay - refresh delay in milliseconds

updateLastModified

protected void updateLastModified()

Update the last modified time.

hasChanged

protected boolean hasChanged()

Check if the configuration has changed since the last time it was loaded.

Returns:

a flag whether the configuration has changed

getFile

protected File getFile()

Returns the file that is monitored by this strategy. Note that the return value can be null under some circumstances.

Returns:

the monitored file