watcherslave.java

移动Agent编程IBM开发的移动Agent编程工具Aglet 采用纯Java编写可移植性好这是用它写的一些例子用于初级入门

/*
 * @(#)WatcherSlave.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.
 */

package examples.watcher;

import com.ibm.aglet.*;
import com.ibm.aglet.event.*;
import java.io.IOException;
import java.net.URL;
import java.util.*;

/**
 * @version     1.00    $Date: 1999/10/27 05:16:39 $
 * @author      Mitsuru Oshima
 */
public class WatcherSlave extends Aglet {
    AgletProxy master;
    boolean started = false;

    public void onCreation(Object o) {
	if (o instanceof AgletID) {
	    master = getAgletContext().getAgletProxy((AgletID)o);
	} else if (o instanceof AgletProxy) {
	    master = (AgletProxy)o;
	} else {
	    master = null;
	}

	//
	// Activate if these messages arrives.
	//
	getMessageManager().setPriority("start",
					MessageManager.ACTIVATE_AGLET);
	getMessageManager().setPriority(Message.DISPOSE,
					MessageManager.ACTIVATE_AGLET);

	//
	// event listener
	//
	addPersistencyListener(new PersistencyAdapter() {
	    public void onActivation(PersistencyEvent ev) {
		setText("wakeup");
		//
		// Start monitoring if it was monitoring
		//
		if (started) {
		    started = false;
		    start();
		}
	    }
	});
	addMobilityListener(new MobilityAdapter() {
	    public void onArrival(MobilityEvent ev) {
		setText("arrived");
		//
		// Start monitoring if it was monitoring
		//
		if (started) {
		    started = false;
		    start();
		}
	    }
	});
    }

    public boolean handleMessage(Message msg) {
	if (msg.sameKind("start")) {

	    // to work around a bug in framework..... sorry.
	    msg.sendReply();

	    start();
	} else if (msg.sameKind("stop")) {
	    stop();

	} else if (msg.sameKind("gonext")) {
	    try {
		dispatch((URL)msg.getArg());
	    } catch (Exception ex) {
		ex.printStackTrace();
	    }

	} else if (msg.sameKind("sleep")) {
	    
	    // sleep at most 10 seconds.
	    try {
		deactivate(10 * 1000);
	    } catch (IOException ex) {
		ex.printStackTrace();
	    }
	} else if (msg.sameKind("getInfo")) {
	    msg.sendReply( getInfo() );

	} else return false;
	return true;
    }

    /**
     * Start monitoring
     */
    public void start() {
	if (started || master == null) {
	    return;
	}
	setText("started");
	started = true;

	while(started) {
	    try {
		master.sendAsyncMessage(new Message("update", getInfo()));
	    } catch (InvalidAgletException ex) {
		ex.printStackTrace();
		dispose();
	    }
	    waitMessage(2 * 1000); // wait two seconds.
	}
	setText("stopped");
    }

    public String getInfo() {
	AgletContext ac = getAgletContext();
	StringBuffer b = new StringBuffer();

	Enumeration e = ac.getAgletProxies(ACTIVE|INACTIVE);
	while(e.hasMoreElements()) {
	    try {
		AgletProxy p = (AgletProxy)e.nextElement();
		AgletInfo info = p.getAgletInfo();
		b.append(info.toString());
		b.append("\n---------\n");
	    } catch (InvalidAgletException ex) {
		b.append("[InvalidAglet]\n");
		continue;
	    }
	}
	return b.toString();
    }


    public void stop() {
	started = false;
	notifyMessage();
    }
}