org.nanocontainer.deployer.FolderContentPoller Maven / Gradle / Ivy

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package org.nanocontainer.deployer;

import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystemException;
import org.picocontainer.Startable;

/**
 * Component that polls a folder for children at regular intervals.
 * @author Aslak Hellesøy
 * @version $Revision: 2343 $
 */
public class FolderContentPoller implements Startable {
    private FolderContentHandler folderContentHandler;
    private FileObject folder;

    private Runnable poller = new Runnable() {
        public void run() {
            while (!Thread.interrupted()) {
                try {
                    // Have to "close" the folder to invalidate child cache
                    folder.close();
                    FileObject[] currentChildren = folder.getChildren();
                    folderContentHandler.setCurrentChildren(currentChildren);
                    synchronized(FolderContentPoller.this) {
                        FolderContentPoller.this.notify();
                        FolderContentPoller.this.wait(2000);
                    }
                } catch (FileSystemException e) {
                    e.printStackTrace();
                } catch (InterruptedException e) {
                    thread.interrupt();
                }
            }
        }
    };
    private Thread thread;
    private boolean started = false;


    public FolderContentPoller(FolderContentHandler folderChangeNotifier) {
        this.folderContentHandler = folderChangeNotifier;
        folder = folderChangeNotifier.getFolder();
    }

    public void start() {
        if(started) throw new IllegalStateException("Already started");
        thread = new Thread(poller);
        thread.start();
        started = true;
    }

    public void stop() {
        if(!started) throw new IllegalStateException("Already stopped");
        thread.interrupt();
        started = true;
    }

}