watcher.java

aglet的部分源码

package examples.patterns;

/*
 * @(#)Watcher.java
 * 
 * 03L7246 (c) Copyright IBM Corp. 1996, 1998
 * 
 * The program is provided "as is" without any warranty express or
 * implied, including the warranty of non-infringement and the implied
 * warranties of merchantibility and fitness for a particular purpose.
 * IBM will not be liable for any damages suffered by you as a result
 * of using the Program. In no event will IBM be liable for any
 * special, indirect or consequential damages or lost profits even if
 * IBM has been advised of the possibility of their occurrence. IBM
 * will not be liable for any third party claims against you.
 */

import com.ibm.aglet.*;
import com.ibm.agletx.patterns.*;
import com.ibm.aglet.util.*;

import java.net.URL;
import java.net.MalformedURLException;
import java.io.IOException;

import java.util.Vector;
import java.util.Hashtable;

/**
 * Class Watcher is used to check the update of a file located
 * in a remote aglet server. Given an URL and a file pathname, it will
 * dispatch a slave (the WatcherNotifier instance) to 'watch' update of a file.
 * The slave will not return to the master aglet. While at the remote server,
 * the slave may dispatch a file update report to the master. This is a part
 * of the Messenger usage pattern. Watcher is acting as a receiver in
 * this pattern.
 * 
 * @see Watcher
 * @see WatcherWindow
 * @version     1.00     96/12/28
 * @author      Danny B. Lange
 * @author      Yoshiaki Mima
 * @author      Yariv Aridor
 */

public class Watcher extends SampleAglet {
	private final static String NotifierClassName = 
		"examples.patterns.WatcherNotifier";
	private double interval = 0.0;
	private double duration = 0.0;
	private boolean stay = false;
	private String path = "";

	protected void createSlave(Vector destinations, Object obj) {
		try {
			Notifier.create(null, NotifierClassName, getAgletContext(), this, 
							(URL)(destinations.firstElement()), interval, 
							duration, stay, path);
		} catch (IOException ae) {
			setTheMessage("Notifier Aglet creation failed...");
		} catch (AgletException ae) {
			setTheMessage("Notifier Aglet creation failed...");
		} 
	}
	/*
	 * public void onCreation (Object o) {
	 * super.onCreation(o);
	 * try {
	 * _msw = new WatcherWindow(this);
	 * updateWindow();
	 * } catch (Exception e) {
	 * inError(e.getMessage());
	 * }
	 * }
	 */

	public void createWindow() {
		try {
			_msw = new WatcherWindow(this);
			updateWindow();
		} catch (Exception e) {
			inError(e.getMessage());
		} 
	}
	/**
	 * Creates and sets up the WatcherNotifier with the necessary information to
	 * dispatch to a remote aglet server and hopefully stay there successfully.
	 * This method is a callback method for the interaction window.
	 * @param itinerary contains the destination URL.
	 */
	protected void go(URL destination, double interval, double duration, 
					  boolean stay, String path) {
		this.interval = interval;
		this.duration = duration;
		this.stay = stay;
		this.path = path;

		super.go(destination);
	}
	public boolean handleMessage(Message msg) {
		if (msg.sameKind("notification")) {
			message((Arguments)(msg.getArg()));
		} else {
			super.handleMessage(msg);
		}
		return true;
	}
	/**
	 * Implements the message interface of a receiver. This method is
	 * a part of the Messenger usage pattern.
	 * @Messenger m Messanger aglet that has returened from a slave aglet.
	 * @Object message Message returned.
	 */
	private synchronized void message(Arguments message) {
		int type = ((Integer)message.getArg("type")).intValue();

		if (type == Notifier.NOTIFICATION) {
			_msw.appendResult("UPDATE: " 
							  + (String)(message.getArg("message")) 
							  + ", AT: " + message.getArg("date").toString());
		} else {
			setTheMessage((String)(message.getArg("message")));
		} 
	}
}