Class DefaultFileMonitor

  • All Implemented Interfaces:
    java.lang.Runnable, FileMonitor

    public class DefaultFileMonitor
    extends java.lang.Object
    implements java.lang.Runnable, FileMonitor
    A polling FileMonitor implementation.

    The DefaultFileMonitor is a Thread based polling file system monitor with a 1 second delay.

    Design:

    There is a Map of monitors known as FileMonitorAgents. With the thread running, each FileMonitorAgent object is asked to "check" on the file it is responsible for. To do this check, the cache is cleared.

    • If the file existed before the refresh and it no longer exists, a delete event is fired.
    • If the file existed before the refresh and it still exists, check the last modified timestamp to see if that has changed.
    • If it has, fire a change event.

    With each file delete, the FileMonitorAgent of the parent is asked to re-build its list of children, so that they can be accurately checked when there are new children.
    New files are detected during each "check" as each file does a check for new children. If new children are found, create events are fired recursively if recursive descent is enabled.

    For performance reasons, added a delay that increases as the number of files monitored increases. The default is a delay of 1 second for every 1000 files processed.


    Example usage:

     FileSystemManager fsManager = VFS.getManager();
     FileObject listendir = fsManager.resolveFile("/home/username/monitored/");
     

    DefaultFileMonitor fm = new DefaultFileMonitor(new CustomFileListener()); fm.setRecursive(true); fm.addFile(listendir); fm.start();

    (where CustomFileListener is a class that implements the FileListener interface.)
    Version:
    $Revision: 484943 $ $Date: 2006-12-09 08:42:06 +0100 (Sat, 09 Dec 2006) $
    Author:
    Christopher Ottley
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addFile​(FileObject file)
      Adds a file to be monitored.
      int getChecksPerRun()
      get the number of files to check per run
      long getDelay()
      Get the delay between runs
      boolean isRecursive()
      Access method to get the recursive setting when adding files for monitoring.
      protected void queueAddFile​(FileObject file)
      Queues a file for addition to be monitored.
      protected void queueRemoveFile​(FileObject file)
      Queues a file for removal from being monitored.
      void removeFile​(FileObject file)
      Removes a file from being monitored.
      void run()
      Asks the agent for each file being monitored to check its file for changes.
      void setChecksPerRun​(int checksPerRun)
      set the number of files to check per run.
      void setDelay​(long delay)
      Set the delay between runs
      void setRecursive​(boolean newRecursive)
      Access method to set the recursive setting when adding files for monitoring.
      void start()
      Starts monitoring the files that have been added.
      void stop()
      Stops monitoring the files that have been added.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • DefaultFileMonitor

        public DefaultFileMonitor​(FileListener listener)
    • Method Detail

      • isRecursive

        public boolean isRecursive()
        Access method to get the recursive setting when adding files for monitoring.
      • setRecursive

        public void setRecursive​(boolean newRecursive)
        Access method to set the recursive setting when adding files for monitoring.
      • queueRemoveFile

        protected void queueRemoveFile​(FileObject file)
        Queues a file for removal from being monitored.
      • getDelay

        public long getDelay()
        Get the delay between runs
      • setDelay

        public void setDelay​(long delay)
        Set the delay between runs
      • getChecksPerRun

        public int getChecksPerRun()
        get the number of files to check per run
      • setChecksPerRun

        public void setChecksPerRun​(int checksPerRun)
        set the number of files to check per run. a additional delay will be added if there are more files to check
        Parameters:
        checksPerRun - a value less than 1 will disable this feature
      • queueAddFile

        protected void queueAddFile​(FileObject file)
        Queues a file for addition to be monitored.
      • start

        public void start()
        Starts monitoring the files that have been added.
      • stop

        public void stop()
        Stops monitoring the files that have been added.
      • run

        public void run()
        Asks the agent for each file being monitored to check its file for changes.
        Specified by:
        run in interface java.lang.Runnable