communicationtask.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 195 行

package de.fhm.jkf.gui;
/*
 * <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 Marten Wulff
 * <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>
 * 
 * $Log: CommunicationTask.java,v $
 * Revision 1.7  2003/03/12 14:44:25  willaxt
 * adjusted to new error handling code
 *
 * Revision 1.6  2003/02/06 11:51:55  willaxt
 * added javadoc comments
 *
 * Revision 1.5  2003/02/04 21:47:43  willaxt
 * only code formatting, nothing changed in code
 *
 * Revision 1.4  2003/02/01 00:28:16  mwulff
 * calls setBusy on the JKFSubApplicationPanel, for setting the different cursors
 *
 * Revision 1.3  2003/01/30 09:45:12  mwulff
 * no message
 *
 * Revision 1.2  2003/01/16 15:47:47  mwulff
 * know calls the JKFEventQueue to lock and unlock it's JKFView
 *
 * Revision 1.1  2003/01/16 13:10:54  mwulff
 * initial version
 *
 * Revision 1.2  2003/01/05 16:28:37  willaxt
 * added javadoc comments
 *
 * Revision 1.1  2002/12/31 12:18:41  mwulff
 * no message
 *
 */

import java.awt.Container;

import de.fhm.jkf.thread.cl.InterruptableTask;

/**
 * Special abstract class for communication tasks which are
 * processed by the <code>CommunicationThreadPool</code>.
 * 
 * @author		marten wulff
 * @version 	1.0
 * 
 * @see de.fhm.jkf.gui.CommunicationThreadPool
 */
public abstract class CommunicationTask implements InterruptableTask {
	/**
	 * Saves the exception which occured during server communication.
	 * If no <code>Exception</code> occured this member is <code>null</code>.
	 */
	private Exception communicationError = null;

	/**
	 * The panel this task works with.
	 */
	private JKFView panel = null;

	/**
	 * Disable constructing <code>CommunicationTask</code>s without
	 * view we can reference to.
	 */
	private CommunicationTask() {
	}

	/**
	 * Creates a new <code>CommunicationTask</code> with a
	 * panel this task works an. The panel is needed to disable
	 * user input during communication with the server.
	 * 
	 * @param panel the panel this task works with.
	 */
	public CommunicationTask(JKFView panel) {
		this.panel = panel;
	}

	/**
	 * Called when the task starts. Sets the sub application to bussy and
	 * locks the event queue.
	 */
	public final void start() {
		getSubApplicationPanel(panel).setBussy(true);
		JKFEventQueue.lock(getSubApplicationPanel(panel));
	}

	/**
	 * Called when the task stops. Sets the sub application to be not bussy
	 * any more and unlocks the event queue.
	 */
	public final void stop() {
		JKFEventQueue.unlock(getSubApplicationPanel(panel));
		getSubApplicationPanel(panel).setBussy(false);
	}

	/**
	 * Helper method which walks up the component hierarchie to
	 * find the <code>JKFSubApplicationPanel</code> where the
	 * given panel lives in.
	 * 
	 * @param c the <code>Container</code> from which the component
	 * hierarchie is walked up.
	 * @return the sub application panel the panel of this task lives in.
	 */
	private JKFSubApplicationPanel getSubApplicationPanel(Container c) {
		while (!(c instanceof JKFSubApplicationPanel)) {
			c = c.getParent();
			if (c == null) {
				break;
			}
		}

		return (JKFSubApplicationPanel) c;
	}

	/**
	 * Method for presenting the result of a query. Always check
	 * if an error occured during communication with the server.
	 * This is done via the <code>getError()</code> method in
	 * this class.
	 * 
	 * @see de.fhm.jkf.gui.CommunicationTask#getError()
	 */
	public abstract void doPresentation();

	/**
	 * Returns the exception that occured during communication.
	 * If no exception occured, <code>null</code> is returned.
	 * 
	 * @return the <code>Exception</code> which occured,
	 * <code>null</code> otherwise.
	 */
	public Exception getError() {
		return this.communicationError;
	}

	/**
	 * The query that should be performed by the framework should
	 * be implemented in this method.
	 */
	public abstract void doQuery();

	/**
	 * Called if the thread is interrupted. Will be called
	 * from the thread pool.
	 */
	public abstract void interrupt();

	/**
	 * Executed by the thread pool. Calls the
	 * <code>doQuery()</code> method in a new
	 * thread.
	 */
	public final void run() {
		doQuery();
	}

	/**
	 * Returns the panel this task works with.
	 */
	public JKFView getPanel() {
		return panel;
	}

	/**
	 * Called from the <code>CommuncationThreadPool</code> if something
	 * went wrong during the communication. Stores the exception
	 * in the member <code>communicationError</code>.
	 * 
	 * @see de.fhm.jkf.thread.cl.InterruptableTask#getError()
	 */
	public final void handleException(Exception ex) {
		communicationError = ex;
	}
}