org.mmbase.util
Class ResourceWatcher

java.lang.Object
  org.mmbase.util.ResourceWatcher

All Implemented Interfaces:

EventListener, NodeEventListener

Direct Known Subclasses:

RegexpReplacer.PatternWatcher

public abstract class ResourceWatcher

extends Object

implements NodeEventListener

Like FileWatcher but for Resources. If (one of the) file(s) to which the resource resolves to is added or changed, it's onChange will be triggered, if not a 'more important' wil was existing already. If a file is removed, and was the most important one, it will be removed from the filewatcher.

Since:

MMBase-1.8

Version:

$Id: ResourceWatcher.java,v 1.13 2006/04/18 13:07:55 michiel Exp $

Author:

Michiel Meeuwissen

See Also:

FileWatcher, ResourceLoader

Nested Class Summary

protected class

ResourceWatcher.ResourceFileWatcher A FileWatcher associated with a certain resource of this ResourceWatcher.

Field Summary

protected Map	fileWatchers Wrapped FileWatcher for watching the file-resources.
protected Map	nodeNumberToResourceName When a resource is loaded from a Node, we must know which Nodes correspond to which resource.
protected ResourceLoader	resourceLoader The resource-loader associated with this ResourceWatcher.
protected SortedSet	resources All resources watched by this ResourceWatcher.

Constructor Summary

protected	ResourceWatcher() Constructor, defaulting to the Root ResourceLoader (see ResourceLoader.getConfigurationRoot()).
protected	ResourceWatcher(ResourceLoader rl) Constructor.

Method Summary

void	add(String resourceName)
void	add(URL url) If you resolved a resource already to an URL, you can still add it for watching.
void	clear() Removes all resources.
protected void	createFileWatcher(String resource) When a resource is added to this ResourceWatcher, this method is called to create a ResourceWatcher.ResourceFileWatcher, and add all files associated with the resource to it.
void	exit() Stops watching.
ResourceLoader	getResourceLoader() The associated ResourceLoader
Set	getResources()
protected boolean	mapNodeNumber(String resource) When a resource is added to this ResourceWatcher, this method is called to check wether a ResourceBuilder node is associated with this resource.
void	notify(NodeEvent event) If a node (of the type 'resourceBuilder') changes, checks if it is a node belonging to one of the resource of this resource-watcher.
void	onChange() Calls onChange(String) for every added resource.
abstract void	onChange(String resourceName) Put here the stuff that has to be executed, when a file has been changed.
void	remove(String resourceName)
void	setDelay(long delay) Set the delay to observe between each check of the file changes.
void	start()
String	toString() Shows the 'contents' of the filewatcher.

Methods inherited from class java.lang.Object

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

Field Detail

resources

protected SortedSet resources

All resources watched by this ResourceWatcher. A Set of Strings. Often, a ResourceWatcher would watch only one resource.

nodeNumberToResourceName

protected Map nodeNumberToResourceName

When a resource is loaded from a Node, we must know which Nodes correspond to which resource. You could ask the node itself, but if the node happens to be deleted, then you can't know that any more. Used in notify(NodeEvent)

fileWatchers

protected Map fileWatchers

Wrapped FileWatcher for watching the file-resources. ResourceName -> FileWatcher.

resourceLoader

protected ResourceLoader resourceLoader

The resource-loader associated with this ResourceWatcher.

Constructor Detail

ResourceWatcher

protected ResourceWatcher(ResourceLoader rl)

Constructor.

ResourceWatcher

protected ResourceWatcher()

Constructor, defaulting to the Root ResourceLoader (see ResourceLoader.getConfigurationRoot()).

Method Detail

getResources

public Set getResources()

Returns:

Unmodifiable set of String of watched resources

getResourceLoader

public ResourceLoader getResourceLoader()

The associated ResourceLoader

add

public void add(String resourceName)

Parameters:

resourceName - The resource to be monitored.

add

public void add(URL url)

If you resolved a resource already to an URL, you can still add it for watching.

createFileWatcher

protected void createFileWatcher(String resource)

When a resource is added to this ResourceWatcher, this method is called to create a ResourceWatcher.ResourceFileWatcher, and add all files associated with the resource to it.

mapNodeNumber

protected boolean mapNodeNumber(String resource)

When a resource is added to this ResourceWatcher, this method is called to check wether a ResourceBuilder node is associated with this resource. If so, this methods maps the number of the node to the resource name. This is needed in notify(NodeEvent) in case of a node-deletion.

Returns:

Whether a Node as found to map.

notify

public void notify(NodeEvent event)

If a node (of the type 'resourceBuilder') changes, checks if it is a node belonging to one of the resource of this resource-watcher. If so, onChange(java.lang.String) is called.

Specified by:

notify in interface NodeEventListener

start

public void start()

onChange

public abstract void onChange(String resourceName)

Put here the stuff that has to be executed, when a file has been changed.

Parameters:

resourceName - The resource that was changed.

onChange

public final void onChange()

Calls onChange(String) for every added resource.

setDelay

public void setDelay(long delay)

Set the delay to observe between each check of the file changes.

remove

public void remove(String resourceName)

clear

public void clear()

Removes all resources.

exit

public void exit()

Stops watching. Stops all filewatchers, removes observers.

toString

public String toString()

Shows the 'contents' of the filewatcher. It shows a list of files/last modified timestamps.