org.refcodes.component.impls.DeviceAutomatonImpl Maven / Gradle / Ivy

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// /////////////////////////////////////////////////////////////////////////////
// REFCODES.ORG
// =============================================================================
// This code is copyright (c) by Siegfried Steiner, Munich, Germany and licensed
// under the following (see "http://en.wikipedia.org/wiki/Multi-licensing")
// licenses:
// =============================================================================
// GNU General Public License, v3.0 ("http://www.gnu.org/licenses/gpl-3.0.html")
// together with the GPL linking exception applied; as being applied by the GNU
// Classpath ("http://www.gnu.org/software/classpath/license.html")
// =============================================================================
// Apache License, v2.0 ("http://www.apache.org/licenses/LICENSE-2.0")
// =============================================================================
// Please contact the copyright holding author(s) of the software artifacts in
// question for licensing issues not being covered by the above listed licenses,
// also regarding commercial licensing models or regarding the compatibility
// with other open source licenses.
// /////////////////////////////////////////////////////////////////////////////

package org.refcodes.component.impls;

import org.refcodes.component.ConnectionStatus;
import org.refcodes.component.DeviceComponent;
import org.refcodes.component.DeviceComponent.DeviceAutomaton;
import org.refcodes.component.LifeCycleComponent.LifeCycleAutomaton;
import org.refcodes.component.LifeCycleStatus;
import org.refcodes.component.OpenException;

/**
 * This class implements a {@link LifeCycleAutomaton}.
 */
public class DeviceAutomatonImpl implements DeviceAutomaton {

	// /////////////////////////////////////////////////////////////////////////
	// VARIABLES:
	// /////////////////////////////////////////////////////////////////////////

	private ConnectionStatus _connectionStatus = ConnectionStatus.NONE;
	protected DeviceComponent _connectionComponent = null;

	// /////////////////////////////////////////////////////////////////////////
	// CONSTRUCTORS:
	// /////////////////////////////////////////////////////////////////////////

	/**
	 * Empty constructor, such {@link LifeCycleAutomaton} cannot do much more
	 * than decline the various {@link LifeCycleStatus} states for you.
	 */
	public DeviceAutomatonImpl() {}

	/**
	 * This constructor uses a {@link LifeCycleStatus} for wrapping it inside
	 * the {@link DeviceAutomatonImpl}, making sure of obeying and guarding the
	 * correct {@link LifeCycleStatus}'s order of {@link LifeCycleStatus} states
	 * for you.
	 * 
	 * @param aConnectionComponent The component to be guarded regarding the
	 *        correct declination of the {@link LifeCycleStatus} states.
	 */
	public DeviceAutomatonImpl( DeviceComponent aConnectionComponent ) {
		_connectionComponent = aConnectionComponent;
	}

	// /////////////////////////////////////////////////////////////////////////
	// METHODS:
	// /////////////////////////////////////////////////////////////////////////

	@Override
	public synchronized ConnectionStatus getConnectionStatus() {
		return _connectionStatus;
	}

	// /////////////////////////////////////////////////////////////////////////
	// CONVENIANCE METHODS:
	// /////////////////////////////////////////////////////////////////////////

	@Override
	public boolean isOpenable() {
		return (_connectionStatus == ConnectionStatus.NONE) || (isClosed());
	}

	@Override
	public void open() throws OpenException {
		if ( !isOpenable() ) {
			throw new OpenException( "Cannot open as the component is in status <" + _connectionStatus + "> which is not the appropriate status for opening." );
		}
		if ( _connectionComponent != null ) {
			_connectionComponent.open();
		}
		_connectionStatus = ConnectionStatus.OPENED;
	}

	@Override
	public boolean isOpened() {
		return (_connectionStatus == ConnectionStatus.OPENED);
	}

	@Override
	public boolean isClosable() {
		return (_connectionStatus == ConnectionStatus.OPENED);
	}

	@Override
	public boolean isClosed() {
		return (_connectionStatus == ConnectionStatus.CLOSED);
	}

	@Override
	public void close() {
		if ( isOpened() ) {
			try {
				if ( _connectionComponent != null ) {
					_connectionComponent.close();
				}
			}
			catch ( Exception e ) {
				// LOGGER.warn(
				// "While closing the component, an unexpected exception was thrown (close must always work), setting connection status to <"
				// + ConnectionStatus.CLOSED + ">.", e );
			}
		}
		_connectionStatus = ConnectionStatus.CLOSED;
	}
}