org.exolab.castor.mapping
Class GeneralizedFieldHandler

java.lang.Object
  org.exolab.castor.mapping.loader.FieldHandlerFriend
      org.exolab.castor.mapping.ExtendedFieldHandler
          org.exolab.castor.mapping.AbstractFieldHandler
              org.exolab.castor.mapping.GeneralizedFieldHandler

All Implemented Interfaces:

ConfigurableFieldHandler, FieldHandler

Direct Known Subclasses:

EnumFieldHandler, SQLTimeFieldHandler, SQLTimestampFieldHandler, ToStringFieldHandler, ValueOfFieldHandler

public abstract class GeneralizedFieldHandler
extends AbstractFieldHandler

An extended version of the FieldHandler interface which is used for making generic libraries of FieldHandlers which can be used for more than one field or class, but have similar conversion algorithms.

Version:

$Revision: 6216 $ $Date: 2005-01-18 17:29:45 -0700 (Tue, 18 Jan 2005) $

Author:

Keith Visco

See Also:

FieldDescriptor, FieldHandler

Field Summary

Fields inherited from class org.exolab.castor.mapping.AbstractFieldHandler

_properties

Constructor Summary

protected

GeneralizedFieldHandler() Creates a new default GeneralizedFieldHandler.

Method Summary

abstract Object	convertUponGet(Object value) This method is used to convert the value when the getValue method is called.
abstract Object	convertUponSet(Object value) This method is used to convert the value when the setValue method is called.
abstract Class	getFieldType() Returns the class type for the field that this GeneralizedFieldHandler converts to and from.
Object	getValue(Object object) Returns the value of the field from the object.
Object	newInstance(Object parent) Creates a new instance of the object described by this field.
Object	newInstance(Object parent, Object[] args) Creates a new instance of the object described by this field.
void	resetValue(Object object) Sets the value of the field to a default value.
void	setCollectionIteration(boolean autoCollectionIteration) Sets whether or not this GeneralizedFieldHandler should automatically iterate over the collection returned by the target object and pass only the items (one by one) to the convertUponGet method.
void	setFieldHandler(FieldHandler handler) Sets the FieldHandler that this FieldHander delegates to.
void	setValue(Object object, Object value) Sets the value of the field on the object.

Methods inherited from class org.exolab.castor.mapping.AbstractFieldHandler

getFieldDescriptor, hasValue, setConfiguration, setFieldDescriptor

Methods inherited from class org.exolab.castor.mapping.ExtendedFieldHandler

checkValidity

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.exolab.castor.mapping.FieldHandler

checkValidity

Constructor Detail

GeneralizedFieldHandler

protected GeneralizedFieldHandler()

Creates a new default GeneralizedFieldHandler. This method should be called by all extending classes so that any important initialization code will be executed.

Method Detail

convertUponGet

public abstract Object convertUponGet(Object value)

This method is used to convert the value when the getValue method is called. The getValue method will obtain the actual field value from given 'parent' object. This convert method is then invoked with the field's value. The value returned from this method will be the actual value returned by getValue method.

Parameters:

value - the object value to convert after performing a get operation

Returns:

the converted value.

convertUponSet

public abstract Object convertUponSet(Object value)

This method is used to convert the value when the setValue method is called. The setValue method will call this method to obtain the converted value. The converted value will then be used as the value to set for the field.

Parameters:

value - the object value to convert before performing a set operation

Returns:

the converted value.

getFieldType

public abstract Class getFieldType()

Returns the class type for the field that this GeneralizedFieldHandler converts to and from. This should be the type that is used in the object model.

Returns:

the class type of of the field

setFieldHandler

public final void setFieldHandler(FieldHandler handler)

Sets the FieldHandler that this FieldHander delegates to. A call to this method must be made with a non-null FieldHandler before this GeneralizedFieldHandler can be used.

Parameters:

handler - the FieldHandler to delegate to

setCollectionIteration

public void setCollectionIteration(boolean autoCollectionIteration)

Sets whether or not this GeneralizedFieldHandler should automatically iterate over the collection returned by the target object and pass only the items (one by one) to the convertUponGet method. As of Castor 0.9.6 this is true by default.

Parameters:

autoCollectionIteration - a boolean that when true indicates that this GeneralizedFieldHandler should automatically iterate over a collection and pass only collection items to the convertUponGet method.

getValue

public final Object getValue(Object object)
                      throws IllegalStateException

Returns the value of the field from the object.

Specified by:

getValue in interface FieldHandler

Specified by:

getValue in class FieldHandlerFriend

Parameters:

object - The object

Returns:

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

newInstance

public Object newInstance(Object parent)
                   throws IllegalStateException

Creates a new instance of the object described by this field.

Specified by:

newInstance in interface FieldHandler

Specified by:

newInstance in class FieldHandlerFriend

Parameters:

parent - The object for which the field is created

Returns:

A new instance of the field's value

Throws:

IllegalStateException - This field is a simple type and cannot be instantiated

newInstance

public Object newInstance(Object parent,
                          Object[] args)
                   throws IllegalStateException

Creates a new instance of the object described by this field.

Specified by:

newInstance in class ExtendedFieldHandler

Parameters:

parent - The object for which the field is created

args - the set of constructor arguments

Returns:

A new instance of the field's value

Throws:

IllegalStateException - This field is a simple type and cannot be instantiated

resetValue

public final void resetValue(Object object)
                      throws IllegalStateException,
                             IllegalArgumentException

Sets the value of the field to a default value.

Reference fields are set to null, primitive fields are set to their default value, collection fields are emptied of all elements.

Specified by:

resetValue in interface FieldHandler

Specified by:

resetValue in class FieldHandlerFriend

Parameters:

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

IllegalArgumentException

setValue

public final void setValue(Object object,
                           Object value)
                    throws IllegalStateException,
                           IllegalArgumentException

Sets the value of the field on the object.

Specified by:

setValue in interface FieldHandler

Specified by:

setValue in class FieldHandlerFriend

Parameters:

object - The object.

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.

IllegalArgumentException - The value passed is not of a supported type.