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:

FieldHandler

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: 1.2 $ $Date: 2003/04/16 07:15:57 $

Author:

Keith Visco

See Also:

FieldDescriptor, FieldHandler

Method Summary

abstract java.lang.Object	convertUponGet(java.lang.Object value) This method is used to convert the value when the getValue method is called.
abstract java.lang.Object	convertUponSet(java.lang.Object value) This method is used to convert the value when the setValue method is called.
abstract java.lang.Class	getFieldType() Returns the class type for the field that this GeneralizedFieldHandler converts to and from.
java.lang.Object	getValue(java.lang.Object object) Returns the value of the field from the object.
java.lang.Object	newInstance(java.lang.Object parent) Creates a new instance of the object described by this field.
java.lang.Object	newInstance(java.lang.Object parent, java.lang.Object[] args) Creates a new instance of the object described by this field.
void	resetValue(java.lang.Object object) Sets the value of the field to a default value.
void	setFieldHandler(FieldHandler handler) Sets the FieldHandler that this FieldHander delegates to.
void	setValue(java.lang.Object object, java.lang.Object value) Sets the value of the field on the object.

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

hasValue

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

checkValidity

Methods inherited from class java.lang.Object

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

Method Detail

convertUponGet

public abstract java.lang.Object convertUponGet(java.lang.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 java.lang.Object convertUponSet(java.lang.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 java.lang.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

getValue

public final java.lang.Object getValue(java.lang.Object object)
                                throws java.lang.IllegalStateException

Returns the value of the field from the object.

Specified by:

getValue in interface FieldHandler

Specified by:

getValue in class AbstractFieldHandler

Parameters:

object - The object

Returns:

The value of the field

Throws:

java.lang.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 java.lang.Object newInstance(java.lang.Object parent)
                             throws java.lang.IllegalStateException

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

Specified by:

newInstance in interface FieldHandler

Specified by:

newInstance in class AbstractFieldHandler

Parameters:

parent - The object for which the field is created

Returns:

A new instance of the field's value

Throws:

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

newInstance

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

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

Specified by:

newInstance in class AbstractFieldHandler

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:

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

resetValue

public final void resetValue(java.lang.Object object)
                      throws java.lang.IllegalStateException,
                             java.lang.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 AbstractFieldHandler

Parameters:

object - The object

Throws:

java.lang.IllegalStateException - The Java object has changed and is no longer supported by this handler, or the handler is not compatiable with the Java object

java.lang.IllegalArgumentException

setValue

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

Sets the value of the field on the object.

Specified by:

setValue in interface FieldHandler

Specified by:

setValue in class AbstractFieldHandler

Parameters:

object - The object

value - The new value

Throws:

java.lang.IllegalStateException - The Java object has changed and is no longer supported by this handler, or the handler is not compatiable with the Java object

java.lang.IllegalArgumentException