org.springframework.binding.form.support
Class FormModelMediatingValueModel

java.lang.Object
  org.springframework.binding.value.support.AbstractValueModelWrapper
      org.springframework.binding.form.support.FormModelMediatingValueModel

All Implemented Interfaces:

PropertyChangeListener, EventListener, PropertyChangePublisher, DirtyTrackingValueModel, ValueModelWrapper, ValueModel

public class FormModelMediatingValueModel
extends AbstractValueModelWrapper
implements DirtyTrackingValueModel, PropertyChangeListener

A value model wrapper that mediates between the (wrapped) data value model and the derived view value model. Allows for value change event delivery to be disabled.

Use the provided method setDeliverValueChangeEvents(boolean) to enable/disable the event mechanism. This makes it possible to change all valueModels and only then fire all events (as it is used in AbstractFormModel). Events are handled internally by the dirtyChangeListeners and the mediatedValueHolder.

As this is also a DirtyTrackingValueModel, the implementation allows reverting to the original value by using revertToOriginal(), which uses the value stored in originalValue to reset the wrappedValueModel. This originalValue is updated to hold the wrappedValue when using clearDirty().

Small sketch to illustrate the positioning and usage:

 <setup>
 External actor -> FormModelMediatingValueModel -> wrappedValueModel
                   holds originalValue = ori       wrappedValue = ori
                   events = enabled
 
 <use case>
 events disabled -> events = disabled            -> wrappedValue = ori
 write value A   -> delagates to wrappedModel    -> wrappedValue = A
                    originalValue = ori
                    update dirty state
 events enabled  -> events = enabled             -> wrappedValue = A
                    sends events (dirty...)
 clearDirty      -> originalValue = A            -> wrappedValue = A
 OR
 revertToOriginal-> set originalValue on wrapped -> wrappedValue = ori
                    update dirty state                  
 

Author:

Oliver Hutchison

Field Summary

Fields inherited from interface org.springframework.binding.value.support.DirtyTrackingValueModel

DIRTY_PROPERTY

Fields inherited from interface org.springframework.binding.value.ValueModel

VALUE_PROPERTY

Constructor Summary

FormModelMediatingValueModel(ValueModel propertyValueModel)
Constructor which defaults trackDirty=true.

FormModelMediatingValueModel(ValueModel propertyValueModel, boolean trackDirty)
Constructor.

Method Summary

void	addPropertyChangeListener(PropertyChangeListener listener) Register a listener to all properties of this publisher.
void	addPropertyChangeListener(String propertyName, PropertyChangeListener listener) Register a listener to a specific property.
void	addValueChangeListener(PropertyChangeListener listener) Registers the given PropertyChangeListener with this ValueModel.
void	clearDirty() Resets the dirty state of this model to false.
protected void	firePropertyChange(String propertyName, boolean oldValue, boolean newValue) Handles the dirty event firing.
protected ValueChangeDetector	getValueChangeDetector()
boolean	isDirty() Returns true if value held by this model has changed since the last call to reset or the last time a value came up from the inner model.
void	propertyChange(PropertyChangeEvent evt)
void	removePropertyChangeListener(PropertyChangeListener listener) Remove the listener from all properties of this publisher.
void	removePropertyChangeListener(String propertyName, PropertyChangeListener listener) Remove the listener from a specific property.
void	removeValueChangeListener(PropertyChangeListener listener) Deregisters the given PropertyChangeListener from this ValueModel.
void	revertToOriginal() Reverts the value held by this model to the original value at the last call to reset or the last time a value came up from the inner model.
void	setDeliverValueChangeEvents(boolean deliverValueChangeEvents) Enable/disable the event mechanism.
void	setValueChangeDetector(ValueChangeDetector valueChangeDetector)
void	setValueSilently(Object value, PropertyChangeListener listenerToSkip) Sets a new value and if the value has changed notifies all registered value change listeners except for the specified listener to skip.
protected void	updateDirtyState() Check the dirty state and fire events if needed.

Methods inherited from class org.springframework.binding.value.support.AbstractValueModelWrapper

getInnerMostValue, getInnerMostWrappedValueModel, getValue, getWrappedValueModel, setValue

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.binding.value.ValueModel

getValue, setValue

Constructor Detail

FormModelMediatingValueModel

public FormModelMediatingValueModel(ValueModel propertyValueModel)

Constructor which defaults trackDirty=true.

Parameters:

propertyValueModel - the ValueModel to mediate.

FormModelMediatingValueModel

public FormModelMediatingValueModel(ValueModel propertyValueModel,
                                    boolean trackDirty)

Constructor.

Parameters:

propertyValueModel - the valueModel to mediate.

trackDirty - disable/enable dirty tracking.

Method Detail

setValueSilently

public void setValueSilently(Object value,
                             PropertyChangeListener listenerToSkip)

Description copied from interface: ValueModel

Sets a new value and if the value has changed notifies all registered value change listeners except for the specified listener to skip.

Specified by:

setValueSilently in interface ValueModel

Overrides:

setValueSilently in class AbstractValueModelWrapper

Parameters:

value - the value to be set

listenerToSkip - the PropertyChangeListener that should not be notified of this change (may be null).

propertyChange

public void propertyChange(PropertyChangeEvent evt)

Specified by:

propertyChange in interface PropertyChangeListener

setDeliverValueChangeEvents

public void setDeliverValueChangeEvents(boolean deliverValueChangeEvents)

Enable/disable the event mechanism. Makes it possible to control the timing of event firing (delay the events).

When disabling, no dirty events will be fired and the mediating valueHolder will not set it's value. The latter results in not firing other events like valueChangedEvents.

When enabling, original (stored) value is compared to the newer value in the wrapped model and the necessary events are fired (dirty/valueChanged).

Parameters:

deliverValueChangeEvents - boolean to enable/disable event mechanism.

isDirty

public boolean isDirty()

Description copied from interface: DirtyTrackingValueModel

Returns true if value held by this model has changed since the last call to reset or the last time a value came up from the inner model.

Specified by:

isDirty in interface DirtyTrackingValueModel

clearDirty

public void clearDirty()

Description copied from interface: DirtyTrackingValueModel

Resets the dirty state of this model to false.

Specified by:

clearDirty in interface DirtyTrackingValueModel

revertToOriginal

public void revertToOriginal()

Description copied from interface: DirtyTrackingValueModel

Reverts the value held by this model to the original value at the last call to reset or the last time a value came up from the inner model.

Specified by:

revertToOriginal in interface DirtyTrackingValueModel

updateDirtyState

protected void updateDirtyState()

Check the dirty state and fire events if needed.

setValueChangeDetector

public void setValueChangeDetector(ValueChangeDetector valueChangeDetector)

Parameters:

valueChangeDetector - set the ValueChangeDetector to use when checking the dirty state.

getValueChangeDetector

protected ValueChangeDetector getValueChangeDetector()

Returns:

a ValueChangeDetector to use when checking the dirty state.

addValueChangeListener

public void addValueChangeListener(PropertyChangeListener listener)

Description copied from interface: ValueModel

Registers the given PropertyChangeListener with this ValueModel. The listener will be notified if the value has changed. The PropertyChangeEvents delivered to the listener must have the name set to "value". The latter ensures that all ValueModel implementers behave like the AbstractValueModel subclasses.

To comply with the above specification implementers can use the PropertyChangeSupport's #addPropertyChangeListener method that accepts a property name, so that listeners will be invoked only if that specific property has changed.

Specified by:

addValueChangeListener in interface ValueModel

Overrides:

addValueChangeListener in class AbstractValueModelWrapper

Parameters:

listener - the listener to be added

See Also:

AbstractValueModel.addValueChangeListener(PropertyChangeListener)

removeValueChangeListener

public void removeValueChangeListener(PropertyChangeListener listener)

Description copied from interface: ValueModel

Deregisters the given PropertyChangeListener from this ValueModel.

Specified by:

removeValueChangeListener in interface ValueModel

Overrides:

removeValueChangeListener in class AbstractValueModelWrapper

Parameters:

listener - the listener to be removed

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)

Description copied from interface: PropertyChangePublisher

Register a listener to all properties of this publisher.

Specified by:

addPropertyChangeListener in interface PropertyChangePublisher

Parameters:

listener - the PropertyChangeListener to register.

addPropertyChangeListener

public void addPropertyChangeListener(String propertyName,
                                      PropertyChangeListener listener)

Description copied from interface: PropertyChangePublisher

Register a listener to a specific property.

Specified by:

addPropertyChangeListener in interface PropertyChangePublisher

Parameters:

propertyName - the property to monitor.

listener - the PropertyChangeListener to register.

removePropertyChangeListener

public void removePropertyChangeListener(PropertyChangeListener listener)

Description copied from interface: PropertyChangePublisher

Remove the listener from all properties of this publisher.

Specified by:

removePropertyChangeListener in interface PropertyChangePublisher

Parameters:

listener - the PropertyChangeListener to remove.

removePropertyChangeListener

public void removePropertyChangeListener(String propertyName,
                                         PropertyChangeListener listener)

Description copied from interface: PropertyChangePublisher

Remove the listener from a specific property.

Specified by:

removePropertyChangeListener in interface PropertyChangePublisher

Parameters:

propertyName - the property that was being monitored.

listener - the PropertyChangeListener to remove.

firePropertyChange

protected final void firePropertyChange(String propertyName,
                                        boolean oldValue,
                                        boolean newValue)

Handles the dirty event firing.

Parameters:

propertyName - implementation only handles DIRTY_PROPERTY.

oldValue -

newValue -