org.exolab.castor.mapping
Class GeneralizedFieldHandler

java.lang.Object
  extended by org.exolab.castor.mapping.loader.FieldHandlerFriend
      extended by org.exolab.castor.mapping.ExtendedFieldHandler
          extended by org.exolab.castor.mapping.AbstractFieldHandler
              extended by org.exolab.castor.mapping.GeneralizedFieldHandler
All Implemented Interfaces:
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: 1.3 $ $Date: 2005/01/19 00:29:45 $
Author:
Keith Visco
See Also:
FieldDescriptor, FieldHandler

Nested Class Summary
(package private) static class GeneralizedFieldHandler.GFHConverterEnumeration
           
 
Constructor Summary
protected GeneralizedFieldHandler()
          Creates a new default GeneralizedFieldHandler.
 
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 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(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
getFieldDescriptor, hasValue, 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
 

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 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

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 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


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