Class DefaultFileMonitor

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

    public class DefaultFileMonitor
    extends java.lang.Object
    implements java.lang.Runnable, FileMonitor, java.lang.AutoCloseable
    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.)
    • Constructor Summary

      Constructors 
      Constructor Description
      DefaultFileMonitor​(FileListener listener)
      Constructs a new instance with the given listener.
    • Method Summary

      All Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      void addFile​(FileObject file)
      Adds a file to be monitored.
      void close()  
      int getChecksPerRun()
      Gets the number of files to check per run.
      long getDelay()
      Deprecated.
      java.time.Duration getDelayDuration()
      Gets the delay between runs.
      boolean isRecursive()
      Tests 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)
      Sets the number of files to check per run.
      void setDelay​(long delay)
      Deprecated.
      void setDelay​(java.time.Duration delay)
      Sets the delay between runs.
      void setRecursive​(boolean newRecursive)
      Sets 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)
        Constructs a new instance with the given listener.
        Parameters:
        listener - the listener.
    • Method Detail

      • addFile

        public void addFile​(FileObject file)
        Adds a file to be monitored.
        Specified by:
        addFile in interface FileMonitor
        Parameters:
        file - The FileObject to monitor.
      • close

        public void close()
        Specified by:
        close in interface java.lang.AutoCloseable
      • getChecksPerRun

        public int getChecksPerRun()
        Gets the number of files to check per run.
        Returns:
        The number of files to check per iteration.
      • getDelay

        @Deprecated
        public long getDelay()
        Deprecated.
        Gets the delay between runs.
        Returns:
        The delay period in milliseconds.
      • getDelayDuration

        public java.time.Duration getDelayDuration()
        Gets the delay between runs.
        Returns:
        The delay period.
      • isRecursive

        public boolean isRecursive()
        Tests the recursive setting when adding files for monitoring.
        Returns:
        true if monitoring is enabled for children.
      • queueAddFile

        protected void queueAddFile​(FileObject file)
        Queues a file for addition to be monitored.
        Parameters:
        file - The FileObject to add.
      • queueRemoveFile

        protected void queueRemoveFile​(FileObject file)
        Queues a file for removal from being monitored.
        Parameters:
        file - The FileObject to be removed from being monitored.
      • removeFile

        public void removeFile​(FileObject file)
        Removes a file from being monitored.
        Specified by:
        removeFile in interface FileMonitor
        Parameters:
        file - The FileObject to remove from monitoring.
      • 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
      • setChecksPerRun

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

        public void setDelay​(java.time.Duration delay)
        Sets the delay between runs.
        Parameters:
        delay - The delay period.
        Since:
        2.10.0
      • setDelay

        @Deprecated
        public void setDelay​(long delay)
        Deprecated.
        Sets the delay between runs.
        Parameters:
        delay - The delay period in milliseconds.
      • setRecursive

        public void setRecursive​(boolean newRecursive)
        Sets the recursive setting when adding files for monitoring.
        Parameters:
        newRecursive - true if monitoring should be enabled for children.
      • start

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

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