public class FileAlterationObserver extends Object implements Serializable
To use this implementation:
FileAlterationListener implementation(s) that process
the file/directory create, change and delete eventsFileAlterationObserver for
the appropriate directory.FileAlterationMonitor or
run manually.FileAlterationObserver for the directory and register the listeners:
File directory = new File(new File("."), "src");
FileAlterationObserver observer = new FileAlterationObserver(directory);
observer.addListener(...);
observer.addListener(...);
To manually observe a directory, initialize the observer and invoked the
checkAndNotify() method as required:
// intialize
observer.init();
...
// invoke as required
observer.checkAndNotify();
...
observer.checkAndNotify();
...
// finished
observer.finish();
Alternatively, register the oberver(s) with a FileAlterationMonitor,
which creates a new thread, invoking the observer at the specified interval:
long interval = ...
FileAlterationMonitor monitor = new FileAlterationMonitor(interval);
monitor.addObserver(observer);
monitor.start();
...
monitor.stop();
FileFilters to observe only the files and/or directories
that are of interest. This makes it more efficient and reduces the
noise from unwanted file system events.
Commons IO has a good range of useful, ready made File Filter implementations for this purpose.
For example, to only observe 1) visible directories and 2) files with a ".java" suffix
in a root directory called "src" you could set up a FileAlterationObserver in the following
way:
// Create a FileFilter
IOFileFilter directories = FileFilterUtils.and(
FileFilterUtils.directoryFileFilter(),
HiddenFileFilter.VISIBLE);
IOFileFilter files = FileFilterUtils.and(
FileFilterUtils.fileFileFilter(),
FileFilterUtils.suffixFileFilter(".java"));
IOFileFilter filter = FileFilterUtils.or(directories, files);
// Create the File system observer and register File Listeners
FileAlterationObserver observer = new FileAlterationObserver(new File("src"), filter);
observer.addListener(...);
observer.addListener(...);
FileEntry represents the state of a file or directory, capturing
File attributes at a point in time. Custom implementations of
FileEntry can be used to capture additional properties that the
basic implementation does not support. The FileEntry.refresh(File)
method is used to determine if a file or directory has changed since the last
check and stores the current state of the File's properties.FileAlterationListener,
FileAlterationMonitor,
Serialized Form| Modifier | Constructor and Description |
|---|---|
|
FileAlterationObserver(File directory)
Construct an observer for the specified directory.
|
protected |
FileAlterationObserver(FileEntry rootEntry,
FileFilter fileFilter,
IOCase caseSensitivity)
Construct an observer for the specified directory, file filter and
file comparator.
|
|
FileAlterationObserver(File directory,
FileFilter fileFilter)
Construct an observer for the specified directory and file filter.
|
|
FileAlterationObserver(File directory,
FileFilter fileFilter,
IOCase caseSensitivity)
Construct an observer for the specified directory, file filter and
file comparator.
|
|
FileAlterationObserver(String directoryName)
Construct an observer for the specified directory.
|
|
FileAlterationObserver(String directoryName,
FileFilter fileFilter)
Construct an observer for the specified directory and file filter.
|
|
FileAlterationObserver(String directoryName,
FileFilter fileFilter,
IOCase caseSensitivity)
Construct an observer for the specified directory, file filter and
file comparator.
|
| Modifier and Type | Method and Description |
|---|---|
void |
addListener(FileAlterationListener listener)
Add a file system listener.
|
void |
checkAndNotify()
Check whether the file and its chlidren have been created, modified or deleted.
|
void |
destroy()
Final processing.
|
File |
getDirectory()
Return the directory being observed.
|
FileFilter |
getFileFilter()
Return the fileFilter.
|
Iterable<FileAlterationListener> |
getListeners()
Returns the set of registered file system listeners.
|
void |
initialize()
Initialize the observer.
|
void |
removeListener(FileAlterationListener listener)
Remove a file system listener.
|
String |
toString()
Provide a String representation of this observer.
|
public FileAlterationObserver(String directoryName)
directoryName - the name of the directory to observepublic FileAlterationObserver(String directoryName, FileFilter fileFilter)
directoryName - the name of the directory to observefileFilter - The file filter or null if nonepublic FileAlterationObserver(String directoryName, FileFilter fileFilter, IOCase caseSensitivity)
directoryName - the name of the directory to observefileFilter - The file filter or null if nonecaseSensitivity - what case sensitivity to use comparing file names, null means system sensitivepublic FileAlterationObserver(File directory)
directory - the directory to observepublic FileAlterationObserver(File directory, FileFilter fileFilter)
directory - the directory to observefileFilter - The file filter or null if nonepublic FileAlterationObserver(File directory, FileFilter fileFilter, IOCase caseSensitivity)
directory - the directory to observefileFilter - The file filter or null if nonecaseSensitivity - what case sensitivity to use comparing file names, null means system sensitiveprotected FileAlterationObserver(FileEntry rootEntry, FileFilter fileFilter, IOCase caseSensitivity)
rootEntry - the root directory to observefileFilter - The file filter or null if nonecaseSensitivity - what case sensitivity to use comparing file names, null means system sensitivepublic File getDirectory()
public FileFilter getFileFilter()
public void addListener(FileAlterationListener listener)
listener - The file system listenerpublic void removeListener(FileAlterationListener listener)
listener - The file system listenerpublic Iterable<FileAlterationListener> getListeners()
public void initialize() throws Exception
Exception - if an error occurspublic void destroy() throws Exception
Exception - if an error occurspublic void checkAndNotify()
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