abstractresourcewatcher.java

Java编写的目录监视器(DirectoryWatcher)源码 如果对Ｃ＃等微软语言比较熟悉的话

package com.lightspeedleader.directorywatcher;

import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;

public abstract class AbstractResourceWatcher extends IntervalThread implements IResourceWatcher {

    /**
     * The list of listeners to notify when this directory changes.
     */
    private Collection listeners = new LinkedList();

    /**
     * Constructor that takes the directory to watch.
     *
     * @param name            the directory to watch
     * @param intervalSeconds The interval to use when monitoring this
     *                        resource.  I.e., ever x seconds, check this resource to see
     *                        what has changed.
     */
    public AbstractResourceWatcher(int intervalSeconds, String name) {

        //Get the common thread interval stuff set up.
        super(intervalSeconds, name);
    }

    /**
     * Remove all listeners from this watcher.
     */
    public void removeAllListeners() {

        //Clear the list of all listeners
        listeners.clear();
    }

    /**
     * Add a listener to this directory.
     *
     * @param listener the listener to add
     */
    public void addListener(IResourceListener listener) {

        //And add the listener
        listeners.add(listener);
    }

    /**
     * Remove a listener from this watcher.
     *
     * @param listener the listener to remove
     */
    public void removeListener(IResourceListener listener) {

        //Iterate through the listeners and remove the this listener
        listeners.remove(listener);
    }

    /**
     * When an item is added to this resource, this method will be called.  It
     * will fire the onAdd() method of all its listeners, passing in the item
     * that has been added.
     *
     * @param newResource the item that has been added to this resource.
     */
    protected void resourceAdded(Object newResource) {

        //Iterate through the listeners and fire the onAdd method
        Iterator listIt = listeners.iterator();

        while (listIt.hasNext()) {
            ((IResourceListener) listIt.next()).onAdd(newResource);
        }
    }

    /**
     * When an item is changed in this resource, this method will be called.
     * It will fire the onChange() method of all its listeners, passing in
     * the item that has been changed.
     *
     * @param changedResource the item that has been added to this resource.
     */
    protected void resourceChanged(Object changedResource) {

        //Iterate through the listeners and fire the onChange method
        Iterator listIt = listeners.iterator();

        while (listIt.hasNext()) {
            ((IResourceListener) listIt.next()).onChange(changedResource);
        }
    }

    /**
     * When an item is deleted in this resource, this method will be called.
     * It will fire the onChange() method of all its listeners, passing in
     * the item that has been deleted.
     *
     * @param deletedResource the item that has been added to this resource.
     */
    protected void resourceDeleted(Object deletedResource) {

        //Iterate through the listeners and fire the onDelete method
        Iterator listIt = listeners.iterator();

        while (listIt.hasNext()) {
            ((IResourceListener) listIt.next()).onDelete(deletedResource);
        }
    }

    /**
     * When monitoring starts on an item, this method will be called.
     *
     * @param monitoredResource the resource that is now being monitored
     */
    protected void monitoringStarted(Object monitoredResource) {

        //Iterate through the listeners and fire the onStart method
        Iterator listIt = listeners.iterator();

        while (listIt.hasNext()) {
            ((IResourceListener) listIt.next()).onStart(monitoredResource);
        }
    }

    /**
     * When monitoring stops on an item, this method will be called.
     *
     * @param notMonitoredResource the resource that is not being monitored anymore.
     */
    protected void monitoringStopped(Object notMonitoredResource) {

        //Iterate through the listeners and fire the onStop method
        Iterator listIt = listeners.iterator();

        while (listIt.hasNext()) {
            ((IResourceListener) listIt.next()).onStop(notMonitoredResource);
        }
    }

    /**
     * The interval has expired and now it's time to do something.
     */
    protected abstract void doInterval();
}