Package jakarta.faces.view

Class StateManagementStrategy

java.lang.Object

jakarta.faces.view.StateManagementStrategy

public abstract class StateManagementStrategy
extends Object

Encapsulate the saving and restoring of the view to enable the VDL to take over the responsibility for handling this feature. Because ViewDeclarationLanguage.getStateManagementStrategy(jakarta.faces.context.FacesContext, java.lang.String) is required to return null for Jakarta Server Pages views and non-null for views authored in Facelets for Jakarta Server Faces 2, this specification only applies to Facelets for Jakarta Server Faces 2.

Implementations must call UIComponent.visitTree(jakarta.faces.component.visit.VisitContext, jakarta.faces.component.visit.VisitCallback) on the UIViewRoot to perform the saving and restoring of the view in the saveView(jakarta.faces.context.FacesContext) and restoreView(jakarta.faces.context.FacesContext, java.lang.String, java.lang.String) methods, respectively.

Since:

2.0

Constructor Summary

Constructors

Constructor	Description
StateManagementStrategy()

Method Summary

Modifier and Type	Method	Description
abstract UIViewRoot	restoreView(FacesContext context, String viewId, String renderKitId)	Restore the state of the view with information in the request.
abstract Object	saveView(FacesContext context)	Return the state of the current view in an Object that implements Serializable and can be passed to java.io.ObjectOutputStream.writeObject() without causing a java.io.NotSerializableException to be thrown. The default implementation must perform the following algorithm or its semantic equivalent, explicitly performing all the steps listed here.

Methods inherited from class java.lang.Object

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

Constructor Details

StateManagementStrategy

public StateManagementStrategy()

Method Details

saveView

public abstract Object saveView(FacesContext context)

Return the state of the current view in an Object that implements Serializable and can be passed to java.io.ObjectOutputStream.writeObject() without causing a java.io.NotSerializableException to be thrown. The default implementation must perform the following algorithm or its semantic equivalent, explicitly performing all the steps listed here.

1. If the UIViewRoot of the current view is marked transient, return null immediately.

2. Traverse the view and verify that each of the client ids are unique. Throw IllegalStateException if more than one client id are the same.

3. Visit the tree using UIComponent.visitTree(jakarta.faces.component.visit.VisitContext, jakarta.faces.component.visit.VisitCallback). For each node, call StateHolder.saveState(jakarta.faces.context.FacesContext), saving the returned Object in a way such that it can be restored given only its client id. Special care must be taken to handle the case of components that were added or deleted programmatically during this lifecycle traversal, rather than by the VDL.

The implementation must ensure that the StateHolder.saveState(jakarta.faces.context.FacesContext) method is called for each node in the tree.

The data structure used to save the state obtained by executing the above algorithm must be Serializable, and all of the elements within the data structure must also be Serializable.

Parameters:

context - the FacesContext for this request.

Returns:

the saved view state

Since:

2.0

restoreView

public abstract UIViewRoot restoreView(FacesContext context,
 String viewId,
 String renderKitId)

Restore the state of the view with information in the request. The default implementation must perform the following algorithm or its semantic equivalent.

1. As in the case of restore view on an initial request, the view metadata must be restored and properly handled as well. Obtain the ViewMetadata for the current viewId, and from that call ViewMetadata.createMetadataView(jakarta.faces.context.FacesContext). Store the resultant UIViewRoot in the FacesContext. Obtain the state of the UIViewRoot from the state Object returned from ResponseStateManager.getState(jakarta.faces.context.FacesContext, java.lang.String) and pass that to UIViewRoot.restoreViewScopeState(jakarta.faces.context.FacesContext, java.lang.Object).

   Build the view from the markup. For all components in the view that do not have an explicitly assigned id in the markup, the values of those ids must be the same as on an initial request for this view. This view will not contain any components programmatically added during the previous lifecycle run, and it will contain components that were programmatically deleted on the previous lifecycle run. Both of these cases must be handled.

2. Call ResponseStateManager.getState(jakarta.faces.context.FacesContext, java.lang.String) to obtain the data structure returned from the previous call to saveView(jakarta.faces.context.FacesContext).

3. Visit the tree using UIComponent.visitTree(jakarta.faces.component.visit.VisitContext, jakarta.faces.component.visit.VisitCallback). For each node, call StateHolder.restoreState(jakarta.faces.context.FacesContext, java.lang.Object), passing the state saved corresponding to the current client id.

4. Ensure that any programmatically deleted components are removed.

5. Ensure any programmatically added components are added.

The implementation must ensure that the StateHolder.restoreState(jakarta.faces.context.FacesContext, java.lang.Object) method is called for each node in the tree, except for those that were programmatically deleted on the previous run through the lifecycle.

Parameters:

context - the FacesContext for this request

viewId - the view identifier for which the state should be restored

renderKitId - the render kit id for this state.

Returns:

the root of the restored view

Since:

2.0