/*******************************************************************************
* Copyright 2012 Geoscience Australia
*
* 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.
******************************************************************************/
package au.gov.ga.earthsci.worldwind.common.util;
import java.beans.BeanInfo;
import java.beans.DefaultPersistenceDelegate;
import java.beans.Encoder;
import java.beans.Expression;
import java.beans.IntrospectionException;
import java.beans.Introspector;
/**
* Helper class for making enum classes persistent when serializing classes
* containing an enum property. Each enum must be registered with the class
* using the {@link EnumPersistenceDelegate#installFor(Enum[])} method.
*
* @author Michael de Hoog (michael.dehoog@ga.gov.au)
*/
public class EnumPersistenceDelegate extends DefaultPersistenceDelegate
{
private static EnumPersistenceDelegate INSTANCE = new EnumPersistenceDelegate();
/**
* Install the {@link EnumPersistenceDelegate} for each of the provided enum
* values.
*
* @param values
*/
public static void installFor(Enum<?>[] values)
{
Class<?> declaringClass = values[0].getDeclaringClass();
installFor(declaringClass);
for (Enum<?> e : values)
if (e.getClass() != declaringClass)
installFor(e.getClass());
}
protected static void installFor(Class<?> enumClass)
{
try
{
BeanInfo info = Introspector.getBeanInfo(enumClass);
info.getBeanDescriptor().setValue("persistenceDelegate", INSTANCE);
}
catch (IntrospectionException exception)
{
throw new RuntimeException("Unable to persist enumerated type " + enumClass, exception);
}
}
@Override
protected Expression instantiate(Object oldInstance, Encoder out)
{
Enum<?> e = (Enum<?>) oldInstance;
return new Expression(e.getDeclaringClass(), "valueOf", new Object[] { e.name() });
}
@Override
protected boolean mutatesTo(Object oldInstance, Object newInstance)
{
return oldInstance == newInstance;
}
}