org.apache.commons.vfs2.util

Class WeakRefFileListener

java.lang.Object

org.apache.commons.vfs2.util.WeakRefFileListener

All Implemented Interfaces:

FileListener

public class WeakRefFileListener
extends Object
implements FileListener

Wraps a listener with a WeakReference.

Since:

2.0

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	WeakRefFileListener(FileObject file, FileListener listener) Constructs a new instance.

Method Summary

Modifier and Type	Method and Description
void	fileChanged(FileChangeEvent event) Called when a file is changed.
void	fileCreated(FileChangeEvent event) Called when a file is created.
void	fileDeleted(FileChangeEvent event) Called when a file is deleted.
protected FileListener	getListener() Gets the wrapped listener.
static void	installListener(FileObject file, FileListener listener) Install the listener at the given file.

Methods inherited from class java.lang.Object

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

Constructor Detail

WeakRefFileListener

protected WeakRefFileListener(FileObject file,
                              FileListener listener)

Constructs a new instance.

Parameters:

file - the file object.

listener - the file listener.

Method Detail

installListener

public static void installListener(FileObject file,
                                   FileListener listener)

Install the listener at the given file.

This installs a wrapper with a weak reference, so the listener can be collected. The reference to the listener is removed when the first event can't be delivered.

Warning: you cannot remove the listener with fs.removeListener(file, listener) as you do'nt have the wrapper instance at hand.

Method is used by DelegateFileObject, as used for VirtualFileSystem.

Parameters:

file - The FileObject to listen on.

listener - The FileListener

fileChanged

public void fileChanged(FileChangeEvent event)
                 throws Exception

Called when a file is changed.

This will only happen if you monitor the file using FileMonitor.

Specified by:

fileChanged in interface FileListener

Parameters:

event - The FileChangeEvent.

Throws:

Exception - if an error occurs.

fileCreated

public void fileCreated(FileChangeEvent event)
                 throws Exception

Called when a file is created.

Specified by:

fileCreated in interface FileListener

Parameters:

event - The FileChangeEvent.

Throws:

Exception - if an error occurs.

fileDeleted

public void fileDeleted(FileChangeEvent event)
                 throws Exception

Called when a file is deleted.

Specified by:

fileDeleted in interface FileListener

Parameters:

event - The FileChangeEvent.

Throws:

Exception - if an error occurs.

getListener

protected FileListener getListener()
                            throws Exception

Gets the wrapped listener. If it is gone, the WeakRefFileListener wrapper will remove itself from the list of listeners.

Returns:

The FileListener.

Throws:

Exception - if an error occurs.