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Artifact with commonly used I/O functionality and for connection related
issues such as receiving or transmitting data in a unified way.
// /////////////////////////////////////////////////////////////////////////////
// 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.io;
import org.refcodes.component.AbstractConnectableAutomaton;
import org.refcodes.component.CloseException;
import org.refcodes.component.ConnectionStatus;
import org.refcodes.component.OpenException;
/**
* The {@link AbstractByteReceiver} is a base abstract implementation of the
* {@link ByteReceiver} interface providing common functionality for concrete
* real live {@link ByteDatagramReceiver} and {@link ByteBlockReceiver} (=
* {@link ByteReceiver}) implementations.
*
* A blocking queue is used internally to which received datagrams are put via
* {@link #pushDatagram(byte)} and which can be retrieved via
* {@link #readDatagram()}. The {@link #pushDatagram(byte)} method is your hook
* when extending this class.
*
* Make sure your code fetches the datagrams quick enough to prevent filling up
* of the queue. In case the queue is filled up, adding elements via
* {@link #pushDatagram(byte)} to the queue is blocked until elements are taken
* from the queue via {@link #readDatagram()}. So cautions are taken to prevent
* a memory leak.
*/
public abstract class AbstractByteReceiver extends AbstractByteProvider implements ByteReceiver {
// /////////////////////////////////////////////////////////////////////////
// CONSTANTS:
// /////////////////////////////////////////////////////////////////////////
// /////////////////////////////////////////////////////////////////////////
// VARIABLES:
// /////////////////////////////////////////////////////////////////////////
protected ConnectableAutomaton _automaton = new ConnectableAutomaton();
// /////////////////////////////////////////////////////////////////////////
// CONSTRUCTORS:
// /////////////////////////////////////////////////////////////////////////
/**
* Constructs a {@link AbstractByteReceiver} with a default sized blocking
* queue enabling a maximum of {@link #DATAGRAM_QUEUE_SIZE} datagrams.
* -------------------------------------------------------------------------
* Make sure your code fetches the datagrams quick enough to prevent filling
* up of the queue. In case the queue is filled up, adding elements via
* {@link #pushDatagram(byte)} to the queue is blocked until elements are
* taken from the queue via {@link #readDatagram()}.
*/
public AbstractByteReceiver() {
super();
}
/**
* Constructs a {@link AbstractByteReceiver} with a custom sized blocking
* queue enabling a maximum of datagrams as specified by the capacity
* parameter.
* -------------------------------------------------------------------------
* Make sure your code fetches the datagrams quick enough to prevent filling
* up of the queue. In case the queue is filled up, adding elements via
* {@link #pushDatagram(byte)} to the queue is blocked until elements are
* taken from the queue via {@link #readDatagram()}.
*
* @param aCapacity The capacity of the queue holding the received
* datagrams.
*/
public AbstractByteReceiver( int aCapacity ) {
super( aCapacity );
}
// /////////////////////////////////////////////////////////////////////////
// METHODS:
// /////////////////////////////////////////////////////////////////////////
/**
* {@inheritDoc}
*/
@Override
public byte readDatagram() throws OpenException, InterruptedException {
if ( _datagramQueue.isEmpty() && !isOpened() ) {
throw new OpenException( "Unable to read datagram as the connection is NOT OPEN; connection status is " + getConnectionStatus() + "." );
}
return super.readDatagram();
}
/**
* {@inheritDoc}
*/
@Override
public byte[] readDatagrams() throws OpenException, InterruptedException {
if ( _datagramQueue.isEmpty() && !isOpened() ) {
throw new OpenException( "Unable to read datagram as the connection is NOT OPEN; connection status is " + getConnectionStatus() + "." );
}
return super.readDatagrams();
}
/**
* {@inheritDoc}
*/
@Override
public byte[] readDatagrams( int aBlockSize ) throws OpenException, InterruptedException {
if ( _datagramQueue.isEmpty() && !isOpened() ) {
throw new OpenException( "Unable to read datagram as the connection is NOT OPEN; connection status is " + getConnectionStatus() + "." );
}
return super.readDatagrams( aBlockSize );
}
/**
* {@inheritDoc}
*/
@Override
public boolean hasDatagram() throws OpenException {
// Enable the caller to get all elements from the queue:
// if ( _datagramQueue.isEmpty() && !isOpened() ) { throw new
// OpenException( "Unable to read datagram as the connection is NOT
// OPEN; connection status is " + getConnectionStatus() + "." ); }
return !_datagramQueue.isEmpty();
}
/**
* {@inheritDoc}
*/
@Override
public void close() throws CloseException {
if ( isOpened() ) {
_automaton.close();
releaseAll();
}
}
/**
* {@inheritDoc}
*/
@Override
public void releaseAll() {
synchronized ( _datagramQueue ) {
_datagramQueue.notifyAll();
}
}
/**
* {@inheritDoc}
*/
@Override
public boolean isOpened() {
return _automaton.isOpened();
}
/**
* {@inheritDoc}
*/
@Override
public boolean isClosable() {
return _automaton.isClosable();
}
/**
* {@inheritDoc}
*/
@Override
public boolean isClosed() {
return _automaton.isClosed();
}
/**
* {@inheritDoc}
*/
@Override
public ConnectionStatus getConnectionStatus() {
return _automaton.getConnectionStatus();
}
// /////////////////////////////////////////////////////////////////////////
// HOOKS:
// /////////////////////////////////////////////////////////////////////////
/**
* Open.
*
* @throws OpenException the open exception
*/
protected void open() throws OpenException {
_automaton.open();
}
/**
* Sets the connection status.
*
* @param aConnectionStatus the new connection status
*/
protected void setConnectionStatus( ConnectionStatus aConnectionStatus ) {
_automaton.setConnectionStatus( aConnectionStatus );
}
/**
* Checks if is openable.
*
* @return true, if is openable
*/
protected boolean isOpenable() {
return _automaton.isOpenable();
}
///////////////////////////////////////////////////////////////////////////
// INNER CLASSES:
// /////////////////////////////////////////////////////////////////////////
/**
* The Class ConnectableAutomaton.
*/
protected static class ConnectableAutomaton extends AbstractConnectableAutomaton {
/**
* Checks if is openable.
*
* @return true, if is openable
*/
@Override
public boolean isOpenable() {
return super.isOpenable();
}
/**
* Open.
*
* @throws OpenException the open exception
*/
@Override
public void open() throws OpenException {
super.open();
}
/**
* Sets the connection status.
*
* @param aConnectionStatus the new connection status
*/
@Override
public void setConnectionStatus( ConnectionStatus aConnectionStatus ) {
super.setConnectionStatus( aConnectionStatus );
}
};
}