jxtatimer.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: JxtaTimer.java,v 1.7 2002/04/18 16:14:48 bondolo Exp $
 */

package net.jxta.impl.util;

import java.lang.Thread;

import org.apache.log4j.Category;
import org.apache.log4j.Priority;

/**
 * This class implements a simple timer utility.
 *
 * Note that this class is provided only because java.util.Timer was
 * introduced in Java 1.3, and Jxta implementation must be able to run
 * on older Java version (1.1.4).
 *
 * @see net.jxta.util.JxtaTimerHandler
 *
 * @version $Revision: 1.7 $
 * @since JXTA 1.0
 */

public class JxtaTimer implements Runnable {
    
    private final static Category LOG = Category.getInstance(JxtaTimer.class.getName());
    
    private JxtaTimerHandler    handler = null;
    private Thread              thread = null;
    private long                delay = 0;
    private boolean             repeat = false;
    private boolean             finish = false;
    
    /**
     * Timer constructor
     *
     * @param handler is a handler invoked when the timer goes off.
     * @param delay is the delay in milliseconds before the timer goes off.
     * @param repeat is set to false if the timer is supposes to go off only once
     *  and then die, or set to true if the timer is supposed to go off several time
     *  until it is cancelled.
     *
     * @since JXTA 1.0
     */
    
    public JxtaTimer( JxtaTimerHandler handler, long delay, boolean repeat ) {
        
        this.handler = handler;
        this.delay = delay;
        this.repeat = repeat;
        
        if( delay < 1 ) {
            if (LOG.isEnabledFor(Priority.WARN))
                LOG.warn("delay must be > 0");
            throw new IllegalArgumentException( "delay must be > 0" );
        }
        
        String threadName = null;
        if( repeat )
            threadName = "JxtaTimerThread repeat=" + delay + ", handler=" + handler.getClass().getName();
        else
           threadName = "JxtaTimerThread delay=" + delay + ", handler=" + handler.getClass().getName();
            
        this.thread = new Thread( this, threadName );
        this.thread.start();
    }
    
    /**
     * Returns the interval this timer is waiting for.
     *
     * @since JXTA 1.0
     * @return time in milliseconds that this timer is waiting.
     */
    public long getDelay( ) {
        
        return delay;
    }
    
    /**
     *  resets the interval delay to the requested time. If the timer has
     *  already been waiting more than the amount of time specified, it will
     *  perform the callback immediately.
     *
     * @param delay is the delay in milliseconds before the timer goes off.
     * @throws IllegalArgumentException if delay <= 0
     **/
    public synchronized void setDelay( long delay ) {
        
        if( delay <= 0 ) {
            if (LOG.isEnabledFor(Priority.WARN))
                LOG.warn("delay must be > 0");
            throw new IllegalArgumentException( "delay must be > 0" );
        }
                
        this.delay = delay;
        thread.interrupt();     // wake the thread to have it check the delay.
    }
    
    /**
     * returns true if this is a repeating timer
     *
     * @since JXTA 1.0
     * @return true if the timer will repeat once triggered.
     */
    public boolean isRepeating() {
        return repeat;
    }
    
    /**
     * Check if the timer is cancelled.
     *
     * @since JXTA 1.0
     * @return true if the timer has been cancelled otherwise false.
     */
    public synchronized boolean isCancelled() {
        return finish;
    }
    
    /**
     * cancel a pending timer. The timer is destroyed, and the handler is not called.
     *
     * @since JXTA 1.0
     */
    public void cancel() {
        // since isCancelled() needs to synchronized we cannot sync on this
        // whole method because we would deadlock inside run() during the
        // InterruptedException.
        synchronized( this ) {
            finish = true;
        }
        thread.setDaemon(true); // now that this thread is dying, make sure it doesnt keep the vm running.
        thread.interrupt();
    }
    
    /**
     * run method to start the thread timer
     *
     * @since JXTA 1.0
     */
    
    public void run() {
        try {
            long startedWaiting = System.currentTimeMillis();
            
            while( !isCancelled() ) {
                long beenWaiting = System.currentTimeMillis() - startedWaiting;
                
                try {
                    long waitRemaining = delay - beenWaiting;
                    
                    // if there is any time left, wait that long.
                    if( waitRemaining > 0 )
                        Thread.sleep( waitRemaining );
                    
                    handler.signal(this);
                    
                    if( !repeat )
                        break;
                    
                    // reset when we started waiting
                    startedWaiting = System.currentTimeMillis();
                }
                catch( InterruptedException woken ) {
                    Thread.interrupted(); // we noticed the interruption
                    // we will decide in the main loop what to do.
                    continue;
                }
                catch ( Exception thrown ) {
                    if ( LOG.isEnabledFor(Priority.DEBUG) )
                        LOG.debug( "Terminating due to exception : " + Thread.currentThread().getName(), thrown );
                    break;
                }
            }
        } catch( Throwable everything ) {
            if ( LOG.isEnabledFor(Priority.ERROR) )
                LOG.error( "Uncaught Throwable in thread :" + Thread.currentThread().getName(), everything );
        }
    }
}