it.tidalwave.metadata.MetadataItemHolder Maven / Gradle / Ivy
/*******************************************************************************
*
* blueMarine - open source photo workflow
* =======================================
*
* Copyright (C) 2003-2009 by Fabrizio Giudici
* Project home page: http://bluemarine.tidalwave.it
*
*******************************************************************************
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*******************************************************************************
*
* $Id: MetadataItemHolder.java,v b89b0b568aeb 2010/02/17 15:26:52 fabrizio $
*
******************************************************************************/
package it.tidalwave.metadata;
import javax.annotation.CheckForNull;
import javax.annotation.Nonnull;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.Date;
import java.io.Serializable;
import org.openide.util.Parameters;
/*******************************************************************************
*
* This class is used by many parts of this API to wrap an existing bean of
* metadata, in order to add some important properties:
*
*
* available which tells wether the metadata item exists or
* not; as a general policy, an object representing the item is always created
* (eventually empty) so the {@link #get()} method always return a non
* null;latestModificationTime which tells when the item has been
* modified for the last time. Initially this value is set by the item provider
* (e.g. if it read the item from a file, it could be the latest modification
* time of the file); the value might change later if some attributes are edited.
* origin the origin where the idem came from (e.g. "Image",
* "XMP", "Persistence")sourceName the name of the {@link it.tidalwave.metadata.spi.MetadataItemSource} that
* provided the item.
*
* Implementors of providers will have to subclass MetadataItemHolder
* to implement {@link #isAvailable()} with a specific version that matches their
* own metadata item.
*
* API users will never have to instantiate a MetadataItemHolder as the
* correct way to retrieve an instance of it is to call
* {@link Metadata#findOrCreateItem(java.lang.Class, it.tidalwave.metadata.Metadata.FindOption[])
* Metadata.findOrCreateItem()}.
*
* This class supports {@link PropertyChangeListener}s.
*
* @author Fabrizio Giudici
* @version $Id: MetadataItemHolder.java,v b89b0b568aeb 2010/02/17 15:26:52 fabrizio $
*
******************************************************************************/
public abstract class MetadataItemHolder implements Serializable
{
protected final PropertyChangeSupport pcs = new PropertyChangeSupport(this);
public static enum Mode
{
READ_ONLY, READ_WRITE
}
@Nonnull
private final Bean bean;
@CheckForNull
private final String sourceName;
@CheckForNull
private final String origin;
@CheckForNull
private Date latestModificationTime;
private boolean previousAvailable;
/***************************************************************************
*
*
**************************************************************************/
protected final PropertyChangeListener propertyChangeListener = new PropertyChangeListener()
{
@Override
public void propertyChange (@Nonnull final PropertyChangeEvent event)
{
setLatestModificationTime(TimestampProvider.Locator.findTimestampProvider().getTimestamp());
final boolean newAvailable = isAvailable();
if (previousAvailable != newAvailable)
{
pcs.firePropertyChange("available", previousAvailable, newAvailable);
previousAvailable = newAvailable;
}
}
};
/***************************************************************************
*
*
**************************************************************************/
protected MetadataItemHolder (@Nonnull final Bean bean)
{
this(bean, Mode.READ_WRITE);
}
/***************************************************************************
*
*
**************************************************************************/
protected MetadataItemHolder (@Nonnull final Bean bean, @Nonnull final Mode mode)
{
this(bean, null, null, null, mode);
}
/***************************************************************************
*
*
**************************************************************************/
protected MetadataItemHolder (@Nonnull final Bean bean,
@CheckForNull final String sourceName,
@CheckForNull final String origin,
@CheckForNull final Date latestModificationTime)
{
this(bean, sourceName, origin, latestModificationTime, Mode.READ_WRITE);
}
/***************************************************************************
*
*
**************************************************************************/
protected MetadataItemHolder (@Nonnull final Bean bean,
@CheckForNull final String sourceName,
@CheckForNull final String origin,
@CheckForNull final Date latestModificationTime,
@CheckForNull final Mode mode)
{
Parameters.notNull("bean", bean);
this.bean = bean;
this.sourceName = sourceName;
this.origin = origin;
this.latestModificationTime = (latestModificationTime == null) ? null : new Date(latestModificationTime.getTime());
this.previousAvailable = isAvailable();
if (mode == Mode.READ_WRITE)
{
MetadataUtils.addPropertyChangeListener(bean, propertyChangeListener);
}
}
/***************************************************************************
*
* Returns the held bean.
*
* @return the bean
*
**************************************************************************/
@Nonnull
public Bean get()
{
return bean;
}
/***************************************************************************
*
* Returns the origin.
*
* @return the origin
*
**************************************************************************/
@CheckForNull
public String getOrigin()
{
return origin;
}
/***************************************************************************
*
* Returns the source name.
*
* @return the source name
*
**************************************************************************/
@CheckForNull
public String getSourceName()
{
return sourceName;
}
/***************************************************************************
*
* Returns true if the held bean is available,
* false if it is void.
*
* @return the bean availability
*
**************************************************************************/
public abstract boolean isAvailable();
/***************************************************************************
*
* Returns the latest modification time of this object. This property will
* be updated whenever a contained item is updated.
*
* @return the latest modification time
*
**************************************************************************/
@CheckForNull
public Date getLatestModificationTime()
{
return (latestModificationTime == null) ? null : new Date(latestModificationTime.getTime());
}
/***************************************************************************
*
*
**************************************************************************/
public void addPropertyChangeListener (@Nonnull final PropertyChangeListener listener)
{
pcs.addPropertyChangeListener(listener);
}
/***************************************************************************
*
*
**************************************************************************/
public void addPropertyChangeListener (@Nonnull final String propertyName,
@Nonnull final PropertyChangeListener listener)
{
pcs.addPropertyChangeListener(propertyName, listener);
}
/***************************************************************************
*
*
**************************************************************************/
public void removePropertyChangeListener (@Nonnull final PropertyChangeListener listener)
{
pcs.removePropertyChangeListener(listener);
}
/***************************************************************************
*
*
**************************************************************************/
public void removePropertyChangeListener (@Nonnull final String propertyName,
@Nonnull final PropertyChangeListener listener)
{
pcs.removePropertyChangeListener(propertyName, listener);
}
/***************************************************************************
*
*
**************************************************************************/
@Nonnull
public PropertyChangeListener[] getPropertyChangeListeners()
{
return pcs.getPropertyChangeListeners();
}
/***************************************************************************
*
* {@inheritDoc}
*
**************************************************************************/
@Override
@Nonnull
final public String toString()
{
return String.format("%s[%s, %s, %s]", getClass().getSimpleName(), origin, sourceName, bean);
}
/***************************************************************************
*
* {@inheritDoc}
*
**************************************************************************/
@Override
public boolean equals (final Object obj)
{
if (obj == null)
{
return false;
}
if (getClass() != obj.getClass())
{
return false;
}
final MetadataItemHolder other = (MetadataItemHolder) obj;
return this.bean == other.bean;
}
/***************************************************************************
*
* {@inheritDoc}
*
**************************************************************************/
@Override
public int hashCode()
{
return bean.hashCode();
}
/***************************************************************************
*
*
**************************************************************************/
protected void setLatestModificationTime (@Nonnull final Date latestModificationTime)
{
assert latestModificationTime != null;
final Date oldValue = this.latestModificationTime;
this.latestModificationTime = latestModificationTime;
pcs.firePropertyChange("latestModificationTime", oldValue, this.latestModificationTime);
}
}
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