/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Intalio, Inc. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Intalio, Inc. Exolab is a registered
* trademark of Intalio, Inc.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* INTALIO, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 1999-2002 (C) Intalio, Inc. All Rights Reserved.
*
* $Id$
*/
package org.exolab.castor.mapping;
import java.util.Properties;
/**
* An extended version of the FieldHandler interface which is
* used for adding additional functionality while preserving
* backward compatability.
*
* @author <a href="kvisco@intalio.com">Keith Visco</a>
* @version $Revision$ $Date: 2005-08-03 15:11:51 -0600 (Wed, 03 Aug 2005) $
* @see FieldDescriptor
* @see FieldHandler
*/
public abstract class AbstractFieldHandler
extends ExtendedFieldHandler
implements ConfigurableFieldHandler {
/** The FieldDescriptor for the field that this handler is responsible for. */
private FieldDescriptor _descriptor = null;
/** Configuration that can be used by subclasses when needed. */
protected Properties _properties;
/**
* Creates a new default AbstractFieldHandler. This method
* should be called by all extending classes so that any
* important initialization code will be executed.
*/
protected AbstractFieldHandler() {
super();
//-- currently nothing to do, but initialization
//-- code may be needed in the future
}
/**
* Returns the FieldDescriptor for the field that this
* handler is reponsibile for, or null if no FieldDescriptor
* has been set. This method is useful for implementations
* of the FieldHandler interface that wish to obtain information
* about the field in order to make the FieldHandler more generic
* and reusable, or simply for validation purposes.
*
* @return the FieldDescriptor, or null if none exists.
*/
protected final FieldDescriptor getFieldDescriptor() {
return _descriptor;
}
/**
* Sets the FieldDescriptor that this FieldHander is
* responsibile for. By setting the FieldDescriptor, it
* allows the implementation of the FieldHandler methods
* to obtain information about the field itself. This allows
* a particular implementation to become more generic and
* reusable.
*
* @param fieldDesc the FieldDescriptor to set
*/
public void setFieldDescriptor(FieldDescriptor fieldDesc) {
_descriptor = fieldDesc;
}
/**
* Returns true if the "handled" field has a value within the
* given object.
* <p>
* By default this just checks for null. Normally this method
* is needed for checking if a value has been set via a call
* to the setValue method, or if the primitive value has
* been initialized by the JVM.
* </p>
* <p>
* This method should be overloaded for improved value
* checking.
* </p>
*
* @return true if the given object has a value for the handled field
*/
public boolean hasValue(final Object object) {
return (getValue(object) != null);
}
//---------------------------------------/
//- Methods inherited from FieldHandler -/
//---------------------------------------/
/**
* Returns the value of the field from the object.
*
* @param object The object
* @return The value of the field
* @throws IllegalStateException The Java object has changed and
* is no longer supported by this handler, or the handler is not
* compatiable with the Java object
*/
public abstract Object getValue(Object object)
throws IllegalStateException;
/**
* Creates a new instance of the object described by this field.
*
* @param parent The object for which the field is created
* @return A new instance of the field's value
* @throws IllegalStateException This field is a simple type and
* cannot be instantiated
*/
public abstract Object newInstance(Object parent)
throws IllegalStateException;
/**
* Creates a new instance of the object described by this field.
*
* @param parent The object for which the field is created
* @param args the set of constructor arguments
* @return A new instance of the field's value
* @throws IllegalStateException This field is a simple type and
* cannot be instantiated
*/
public abstract Object newInstance(Object parent, Object[] args)
throws IllegalStateException;
/**
* Sets the value of the field to a default value.
* <p>
* Reference fields are set to null, primitive fields are set to
* their default value, collection fields are emptied of all
* elements.
*
* @param object The object
* @throws IllegalStateException The Java object has changed and
* is no longer supported by this handler, or the handler is not
* compatiable with the Java object
*/
public abstract void resetValue(Object object)
throws IllegalStateException, IllegalArgumentException;
/**
* Sets the value of the field on the object.
*
* @param object The object.
* @param value The new value.
* @throws IllegalStateException The Java object has changed and is no longer
* supported by this handler, or the handler is not compatiable with the
* Java object.
* @throws IllegalArgumentException The value passed is not of a supported type.
*/
public abstract void setValue(Object object, Object value)
throws IllegalStateException, IllegalArgumentException;
/**
* Empty implementation of the {@link ConfigurableFieldHandler} interface, for convenience
* purpose. Subclasses that want to use any configuration should override this method.
*/
public void setConfiguration(final Properties config) throws ValidityException { }
}