serverthread.java

来自「主要是对串口驱动的的一些控制源码！！！ 在下载javacomm20-win32」· Java 代码 · 共 166 行

package de.fhm.jkf.thread.cl;
/*
 * <br><br><center><table border="1" width="80%"><hr>
 * <strong><a href="http://jkf.sourceforge.net">The JKF Project</a></strong>
 * <p>
 * Copyright (C) 2002 by Theodor Willax
 * <p>
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * <p>
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * <p>
 * You should have received a copy of the <a href="http://www.gnu.org/copyleft/lesser.html">
 * GNU Lesser General Public License</a> along with this library; if not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA  02111-1307  USA
 * <hr></table></center>
 */

import java.util.Collection;
import java.util.Iterator;
import java.util.Vector;

/**
 * A <code>ServerThread</code> is a <code>Thread</code> which completes
 * a task if one is given, or waits so long until it gets one.
 * 
 * @author Theodor Willax
 */
public class ServerThread extends Thread {
	/**
	 * The task this <code>ServerThread</code> has to do.
	 */
	private InterruptableTask task = null;
	/**
	 * Is this <code>ServerThread</code> busy?
	 */
	private boolean busy = false;
	/**
	 * Is this <code>ServerThread</code> interrupted?
	 */
	private boolean isInterrupted = false;
	/**
	 * This objects are listener on this <code>ServerThread</code>.
	 */
	private Collection listeners = new Vector();

	/**
	 * Creates a new <code>ServerThread</code> with the given name.
	 * 
	 * @param name The name for this thread.
	 */
	public ServerThread(String name) {
		super(name);
	}

	/**
	 * As long as this <code>ServerThread</code> is not interrupted,
	 * he calls the <code>run</code> method on the actual task. Is
	 * no task available, this <code>ServerThread</code> waits for
	 * a new task.
	 */
	public synchronized void run() {
		while (!isInterrupted) {
			while (task == null) {
				try{
					wait();
				}catch(InterruptedException ignored) {}
			}
			
			try {
				task.start();
				System.out.println("Starting task");
				task.run();
				System.out.println("Finished task");
			} catch (Exception e) {
				task.handleException(e);
			} finally {
				taskReady();
			}
		}
	}

	/**
	 * Gives this <code>ServerThread</code> a new task to run. Calls
	 * internally <code>notify</code>, so the thread starts to work.
	 */
	public synchronized void runTask(InterruptableTask t) {
		busy = true;
		task = t;
		notify();
	}

	/**
	 * Interrupts the work on the actual task. This <code>ServerThread</code>
	 * delegates the call to the task. The task itself is responsible for
	 * interrupting at a defiend position.
	 * 
	 * @see de.fhm.jkf.thread.cl.InterruptableTask#interrupt
	 */
	public void interruptTask() {
		if (task != null)
			task.interrupt();
	}

	/**
	 * Shows if this <code>ServerThread</code> is busy.
	 * 
	 * @return true if this <code>ServerThread</code> is busy, false otherwise.
	 */
	public boolean isBusy() {
		return busy;
	}

	/**
	* Adds listeners which like to be notified, if a task
	* is ready.
	*/
	public void addTaskReadyListener(TaskReadyListener l) {
		listeners.add(l);
	}

	/**
	 * Removes listeners from, whick liked to be notified, if a task
	 * was ready.
	 */
	public void removeTaskReadyListener(TaskReadyListener l) {
		listeners.remove(l);
	}

	/**
	 * Interrupts this <code>ServerThread</code>, not only the task.
	 */
	public void interrupt() {
		super.interrupt();
		isInterrupted = true;
	}

	/**
	 * Signals all listeners that work on this task has ended. Every
	 * listener gets a reference to this <code>ServerThread</code> so
	 * a new task can be added.
	 */
	protected void taskReady() {
		for (Iterator it = listeners.iterator(); it.hasNext();) {
			((TaskReadyListener) it.next()).taskReady(this);
		}
		busy = false;
		task = null;
	}

	/**
	 * Returns the task which is executed at this moment
	 * 
	 * @return the actual task.
	 */
	public InterruptableTask getTask() {
		return task;
	}
}