Module jakarta.faces

Package jakarta.faces.view

Class ViewDeclarationLanguage

java.lang.Object

jakarta.faces.view.ViewDeclarationLanguage

Direct Known Subclasses:

ViewDeclarationLanguageWrapper, ViewHandlingStrategy

public abstract class ViewDeclarationLanguage
extends Object

The contract that a view declaration language must implement to interact with the Jakarta Faces runtime. An implementation of this class must be thread-safe.

Instances of this class are application scoped and must be obtained from the ViewDeclarationLanguageFactory.

Since:

2.0

Field Summary

Fields

Modifier and Type	Field	Description
static final String	FACELETS_VIEW_DECLARATION_LANGUAGE_ID	Identifier for the Facelets view declaration language.

Constructor Summary

Constructors

Constructor	Description
ViewDeclarationLanguage()

Method Summary

Modifier and Type	Method	Description
abstract void	buildView(FacesContext context, UIViewRoot root)	Take any actions specific to this VDL implementation to cause the argument UIViewRoot which must have been created via a call to createView(jakarta.faces.context.FacesContext, java.lang.String), to be populated with children.
List<String>	calculateResourceLibraryContracts(FacesContext context, String viewId)	Return the list of resource library contracts that will be made available for use in the view specified by the argument viewId.
UIComponent	createComponent(FacesContext context, String taglibURI, String tagName, Map<String,Object> attributes)	Create a component given a ViewDeclarationLanguage specific tag library URI and tag name.
abstract UIViewRoot	createView(FacesContext context, String viewId)	Create a UIViewRoot from the VDL contained in the artifact referenced by the argument viewId.
abstract BeanInfo	getComponentMetadata(FacesContext context, Resource componentResource)	Return a reference to the component metadata for the composite component represented by the argument componentResource, or null if the metadata cannot be found.
String	getId()	Returns a non-null String that can be used to identify this view declaration language.
abstract Resource	getScriptComponentResource(FacesContext context, Resource componentResource)	Take implementation specific action to discover a Resource given the argument componentResource.
abstract StateManagementStrategy	getStateManagementStrategy(FacesContext context, String viewId)	For implementations that want to control the implementation of state saving and restoring, the StateManagementStrategy allows them to do so.
abstract ViewMetadata	getViewMetadata(FacesContext context, String viewId)	Return a reference to the view metadata for the view represented by the argument viewId, or null if the metadata cannot be found.
Stream<String>	getViews(FacesContext facesContext, String path, int maxDepth, ViewVisitOption... options)	Return a Stream possibly lazily populated by walking the view tree rooted at a given initial path.
Stream<String>	getViews(FacesContext facesContext, String path, ViewVisitOption... options)	Return a Stream possibly lazily populated by walking the view tree rooted at a given initial path.
abstract void	renderView(FacesContext context, UIViewRoot view)	Render a view rooted at argumentview.
abstract UIViewRoot	restoreView(FacesContext context, String viewId)	Restore a UIViewRoot from a previously created view.
void	retargetAttachedObjects(FacesContext context, UIComponent topLevelComponent, List<AttachedObjectHandler> handlers)	Assuming the component metadata for argument topLevelComponent has been made available by an earlier call to getComponentMetadata(jakarta.faces.context.FacesContext, jakarta.faces.application.Resource), leverage the component metadata for the purpose of re-targeting attached objects from the top level composite component to the individual AttachedObjectTarget instances inside the composite component.
void	retargetMethodExpressions(FacesContext context, UIComponent topLevelComponent)	Assuming the component metadata for argument topLevelComponent has been made available by an earlier call to getComponentMetadata(jakarta.faces.context.FacesContext, jakarta.faces.application.Resource), leverage the component metadata for the purpose of re-targeting any method expressions from the top level component to the appropriate inner component.
boolean	viewExists(FacesContext context, String viewId)	Tests whether a physical resource corresponding to the specified viewId exists.

Methods inherited from class java.lang.Object

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

Field Details

FACELETS_VIEW_DECLARATION_LANGUAGE_ID

public static final String FACELETS_VIEW_DECLARATION_LANGUAGE_ID

Identifier for the Facelets view declaration language.

Since:

2.1

See Also:

• Constant Field Values

Constructor Details

ViewDeclarationLanguage

public ViewDeclarationLanguage()

Method Details

restoreView

public abstract UIViewRoot restoreView(FacesContext context,
 String viewId)

Restore a UIViewRoot from a previously created view. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation.

Parameters:

context - the FacesContext for this request.

viewId - the identifier for a previously rendered view.

Returns:

the restored view

Throws:

NullPointerException - if any of the arguments are null

getViewMetadata

public abstract ViewMetadata getViewMetadata(FacesContext context,
 String viewId)

Return a reference to the view metadata for the view represented by the argument viewId, or null if the metadata cannot be found. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation. Facelets implementation must return non-null.

Parameters:

context - The FacesContext for this request.

viewId - the view id from which to extract the metadata

Returns:

the view metadata

Throws:

NullPointerException - if any of the arguments are null.

FacesException - if there is an error in obtaining the metadata

Since:

2.0

createView

public abstract UIViewRoot createView(FacesContext context,
 String viewId)

Create a UIViewRoot from the VDL contained in the artifact referenced by the argument viewId. See section 7.7.2"Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation.

Parameters:

context - the FacesContext for this request.

viewId - the identifier of an artifact that contains the VDL syntax that describes this view.

Returns:

the newly created view root

Throws:

NullPointerException - if any of the arguments are null

Since:

2.0

buildView

public abstract void buildView(FacesContext context,
 UIViewRoot root)
                        throws IOException

Take any actions specific to this VDL implementation to cause the argument UIViewRoot which must have been created via a call to createView(jakarta.faces.context.FacesContext, java.lang.String), to be populated with children.

The Facelets implementation must insure that markup comprising the view must be executed, with the UIComponent instances in the view being encountered in the same depth-first order as in other lifecycle methods defined on UIComponent, and added to the view (but not rendered) during the traversal. The runtime must guarantee that the view must be fully populated before any of the following happen.

• The PhaseListener.afterPhase(jakarta.faces.event.PhaseEvent) method of any PhaseListeners attached to the application is called

• The UIViewRoot phase listener installed via UIViewRoot.setAfterPhaseListener(jakarta.el.MethodExpression) or UIViewRoot.addPhaseListener(jakarta.faces.event.PhaseListener) are called.

If the root is already populated with children, the view must still be re-built, but care must be taken to ensure that the existing components are correctly paired up with their VDL counterparts in the VDL page. Also, any system events that would normally be generated during the adding or removing of components from the view must be temporarily disabled during the creation of the view and then re-enabled when the view has been built.

Parameters:

context - the FacesContext for this request

root - the UIViewRoot to populate with children using techniques specific to this VDL implementation.

Throws:

IOException - if view cannot be built for any reason

renderView

public abstract void renderView(FacesContext context,
 UIViewRoot view)
                         throws IOException

Render a view rooted at argumentview. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation.

Parameters:

context - the FacesContext for this request.

view - the UIViewRoot from an early call to createView(jakarta.faces.context.FacesContext, java.lang.String) or restoreView(jakarta.faces.context.FacesContext, java.lang.String).

Throws:

NullPointerException - if any of the arguments are null

IOException - if the view cannot be rendered for any reason

getComponentMetadata

public abstract BeanInfo getComponentMetadata(FacesContext context,
 Resource componentResource)

Return a reference to the component metadata for the composite component represented by the argument componentResource, or null if the metadata cannot be found. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation. Jakarta Server Pages implementations must throw UnsupportedOperationException.

Parameters:

context - The FacesContext for this request.

componentResource - The Resource that represents the component.

Returns:

the component metadata

Throws:

NullPointerException - if any of the arguments are null.

FacesException - if there is an error in obtaining the metadata

UnsupportedOperationException - if this is a Jakarta Server Pages VDL implementation.

Since:

2.0

getScriptComponentResource

public abstract Resource getScriptComponentResource(FacesContext context,
 Resource componentResource)

Take implementation specific action to discover a Resource given the argument componentResource. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation. Jakarta Server Pages implementations must throw UnsupportedOperationException.

Parameters:

context - The FacesContext for this request.

componentResource - The Resource that represents the component.

Returns:

the Resource corresponding to the argument componentResource

Throws:

NullPointerException - if any of the arguments are null.

FacesException - if there is an error in obtaining the script component resource

UnsupportedOperationException - if this is a Jakarta Server Pages VDL implementation.

Since:

2.0

createComponent

public UIComponent createComponent(FacesContext context,
 String taglibURI,
 String tagName,
 Map<String,Object> attributes)

Create a component given a ViewDeclarationLanguage specific tag library URI and tag name. The runtime must support this method operating for the Facelets VDL. Other kinds of ViewDeclarationLanguage may be supported but are not required to be supported. For backward compatibility with decorated ViewDeclrationLanguage implementations that do not override this method, a default implementation is provided that returns null. However, any implementation that is compliant with the version of the specification in which this method was introduced must implement this method.

Parameters:

context - the FacesContext for this request

taglibURI - the fully qualified tag library URI that contains the component

tagName - the name of the tag within that library that exposes the component

attributes - any name=value pairs that would otherwise have been given on the markup that would cause the creation of this component or null if no attributes need be given.

Returns:

the newly created component

Throws:

NullPointerException - if context, taglibURI, or tagName are null

Since:

2.2

retargetAttachedObjects

public void retargetAttachedObjects(FacesContext context,
 UIComponent topLevelComponent,
 List<AttachedObjectHandler> handlers)

Assuming the component metadata for argument topLevelComponent has been made available by an earlier call to getComponentMetadata(jakarta.faces.context.FacesContext, jakarta.faces.application.Resource), leverage the component metadata for the purpose of re-targeting attached objects from the top level composite component to the individual AttachedObjectTarget instances inside the composite component. This method must be called by the ViewDeclarationLanguage implementation when creating the UIComponent tree when a composite component usage is encountered.

An algorithm semantically equivalent to the following must be implemented.

• Obtain the metadata for the composite component. Currently this entails getting the value of the UIComponent.BEANINFO_KEY component attribute, which will be an instance of BeanInfo. If the metadata cannot be found, log an error message and return.

• Get the BeanDescriptor from the BeanInfo.

• Get the value of the AttachedObjectTarget.ATTACHED_OBJECT_TARGETS_KEY from the BeanDescriptor's getValue() method. This will be a List<AttachedObjectTarget>. Let this be targetList.

• For each curHandler entry in the argument handlers

  • Let forAttributeValue be the return from AttachedObjectHandler.getFor().

  • For each curTarget entry in targetList, the first of the following items that causes a match will take this action:

    For each UIComponent in the list returned from curTarget.getTargets(), call curHandler.applyAttachedObject(), passing the FacesContext and the UIComponent.

    and cause this inner loop to terminate.

    • If curHandler is an instance of ActionSourceAttachedObjectHandler and curTarget is an instance of ActionSourceAttachedObjectTarget, and curTarget.getName() is equal to curTargetName, consider it a match.

    • If curHandler is an instance of EditableValueHolderAttachedObjectHandler and curTarget is an instance of EditableValueHolderAttachedObjectTarget, and curTarget.getName() is equal to curTargetName, consider it a match.

    • If curHandler is an instance of ValueHolderAttachedObjectHandler and curTarget is an instance of ValueHolderAttachedObjectTarget, and curTarget.getName() is equal to curTargetName, consider it a match.

    • If curHandler is an instance of BehaviorHolderAttachedObjectHandler and curTarget is an instance of BehaviorHolderAttachedObjectTarget, and either of the following conditions are true,

      • curHandler.getEventName() is not null and is equal to curTargetName.
      • curHandler.getEventName() is null and curTarget.isDefaultEvent() is true.

      consider it a match.

The implementation must support retargeting attached objects from the top level compsite component to targets that are composite and non-composite components.

An implementation is provided that will throw UnsupportedOperationException. A Faces implementation compliant with version 2.0 and beyond of the specification must override this method.

Parameters:

context - the FacesContext for this request.

topLevelComponent - The UIComponent in the view to which the attached objects must be attached. This UIComponent must have its component metadata already associated and available from via the JavaBeans API.

handlers - the tag handlers for the attached objects

Throws:

NullPointerException - if any of the arguments are null.

Since:

2.0

retargetMethodExpressions

public void retargetMethodExpressions(FacesContext context,
 UIComponent topLevelComponent)

Assuming the component metadata for argument topLevelComponent has been made available by an earlier call to getComponentMetadata(jakarta.faces.context.FacesContext, jakarta.faces.application.Resource), leverage the component metadata for the purpose of re-targeting any method expressions from the top level component to the appropriate inner component. For each attribute that is a MethodExpression (as indicated by the presence of a "method-signature" attribute and the absence of a "type" attribute), the following action must be taken:

• Get the value of the targets attribute. If the value is a ValueExpression evaluate it. If there is no targets attribute, let the name of the metadata element be the evaluated value of the targets attribute.

• Interpret targets as a space (not tab) separated list of ids. For each entry in the list:

  • Find the inner component of the topLevelComponent with the id equal to the current list entry. For discussion, this component is called target. If not found, log and error and continue to the next attribute.

  • For discussion the declared name of the attribute is called name.

  • In the attributes map of the topLevelComponent, look up the entry under the key name. Assume the result is a ValueExpression. For discussion, this is attributeValueExpression. If not found, log an error and continue to the next attribute.

  • If name is equal to the string "action", or "actionListener" without the quotes, assume target is an ActionSource.

  • If name is equal to the string "validator", or "valueChangeListener" without the quotes, assume target is an EditableValueHolder.

  • Call getExpressionString() on the attributeValueExpression and use that string to create a MethodExpression of the appropriate signature for name.

  • If name is not equal to any of the previously listed strings, call getExpressionString() on the attributeValueExpression and use that string to create a MethodExpression where the signature is created based on the value of the "method-signature" attribute of the <composite:attribute /> tag.

  • Let the resultant MethodExpression be called attributeMethodExpression for discussion.

  • If name is equal to the string "action" without the quotes, call ActionSource.setActionExpression(jakarta.el.MethodExpression) on target, passing attributeMethodExpression.

  • If name is equal to the string "actionListener" without the quotes, call ActionSource.addActionListener(jakarta.faces.event.ActionListener) on target, passing attributeMethodExpression wrapped in a MethodExpressionActionListener.

  • If name is equal to the string "validator" without the quotes, call EditableValueHolder.addValidator(jakarta.faces.validator.Validator) on target, passing attributeMethodExpression wrapped in a MethodExpressionValidator.

  • If name is equal to the string "valueChangeListener" without the quotes, call EditableValueHolder.addValueChangeListener(jakarta.faces.event.ValueChangeListener) on target, passing attributeMethodExpression wrapped in a MethodExpressionValueChangeListener.

  • Otherwise, assume that the MethodExpression should be placed in the components attribute set. The runtme must create the MethodExpression instance based on the value of the "method-signature" attribute.

An implementation is provided that will throw UnsupportedOperationException. A Faces implementation compliant with version 2.0 and beyond of the specification must override this method.

Parameters:

context - the FacesContext for this request.

topLevelComponent - The UIComponent in the view to which the attached objects must be attached. This UIComponent must have its component metadata already associated and available from via the JavaBeans API.

Throws:

NullPointerException - if context or topLevelComponent is null.

Since:

2.0

calculateResourceLibraryContracts

public List<String> calculateResourceLibraryContracts(FacesContext context,
 String viewId)

Return the list of resource library contracts that will be made available for use in the view specified by the argument viewId. If no match is found, return an empty list. See section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document for the specification of the default implementation. For backward compatibility with prior implementations, an implementation is provided that returns null, but any implementation compliant with the version of the specification in which this method was introduced must implement it as specified in section 7.7.2 "Default ViewDeclarationLanguage Implementation" of the Jakarta Faces Specification Document.

Parameters:

context - the FacesContext for this request

viewId - the view id for which the applicable resource library contracts should be calculated.

Returns:

the calculated list of resource library contract names

Since:

2.2

getStateManagementStrategy

public abstract StateManagementStrategy getStateManagementStrategy(FacesContext context,
 String viewId)

For implementations that want to control the implementation of state saving and restoring, the StateManagementStrategy allows them to do so. Returning null indicates that the implementation wishes the runtime to handle the state saving and restoring. Implementations that provide the VDL for Facelets for Jakarta Faces 2.0 and later must return non-null from this method.

Parameters:

context - the FacesContext for the current request.

viewId - the view id.

Returns:

the strategy as specified above

Since:

2.0

viewExists

public boolean viewExists(FacesContext context,
 String viewId)

Tests whether a physical resource corresponding to the specified viewId exists.

The default implementation uses ResourceHandler.createViewResource(jakarta.faces.context.FacesContext, java.lang.String) to locate the physical resource.

Parameters:

context - The FacesContext for this request.

viewId - the view id to test

Returns:

the result as specified above

Since:

2.1

getViews

public Stream<String> getViews(FacesContext facesContext,
 String path,
 ViewVisitOption... options)

Return a Stream possibly lazily populated by walking the view tree rooted at a given initial path. The view tree is traversed breadth-first, the elements in the stream are logical view ids.

This method works as if invoking it were equivalent to evaluating the expression:

 getViewResources(facesContext, start, Integer.MAX_VALUE, options)
 

Put differently, it visits all levels of the resource tree.

Parameters:

facesContext - The FacesContext for this request.

path - The initial path from which to start looking for views

options - The options to influence the traversal. See ViewVisitOption for details on those.

Returns:

the Stream of view ids

Since:

2.3

getViews

public Stream<String> getViews(FacesContext facesContext,
 String path,
 int maxDepth,
 ViewVisitOption... options)

Return a Stream possibly lazily populated by walking the view tree rooted at a given initial path. The view tree is traversed breadth-first, the elements in the stream are logical view ids.

The maxDepth parameter is the maximum depth of directory levels to visit beyond the initial path, which is always visited. The value is relative to the root (/), not to the given initial path. E.g. given maxDepth = 3 and initial path /foo/, visiting will proceed up to /foo/bar/, where / counts as depth 1, /foo/ as depth 2 and /foo/bar/ as depth 3. A value lower or equal to the depth of the initial path means that only the initial path is visited. A value of MAX_VALUE may be used to indicate that all levels should be visited.

Parameters:

facesContext - The FacesContext for this request.

path - The initial path from which to start looking for views

maxDepth - The absolute maximum depth of nested directories to visit counted from the root (/).

options - The options to influence the traversal. See ViewVisitOption for details on those.

Returns:

the Stream of view ids

Since:

2.3

getId

public String getId()

Returns a non-null String that can be used to identify this view declaration language.

The default implementation returns the fully qualified class name of the view declaration language implementation. Subclasses may override to provide a more meaningful id.

Returns:

the id of this view declaration language

Since:

2.1