javax.faces.application
Class ViewHandler

java.lang.Object
  javax.faces.application.ViewHandler

Direct Known Subclasses:

ViewHandlerWrapper

public abstract class ViewHandler
extends Object

A ViewHandler manages the component-tree-creation and component-tree-rendering parts of a request lifecycle (ie "create view", "restore view" and "render response").

A ViewHandler is responsible for generating the component tree when a new view is requested; see method "createView".

When the user performs a "postback", ie activates a UICommand component within a view, then the ViewHandler is responsible for recreating a view tree identical to the one used previously to render that view; see method "restoreView".

And the ViewHandler is also responsible for rendering the final output to be sent to the user by invoking the rendering methods on components; see method "renderView".

This class also isolates callers from the underlying request/response system. In particular, this class does not explicitly depend upon the javax.servlet apis. This allows JSF to be used on servers that do not implement the servlet API (for example, plain CGI).

Examples:

• A JSP ViewHandler exists for using "jsp" pages as the presentation technology. This class then works together with a taghandler class and a jsp servlet class to implement the methods on this abstract class definition.
• A Facelets ViewHandler instead uses an xml file to define the components and non-component data that make up a specific view.

Of course there is no reason why the "template" needs to be a textual file. A view could be generated based on data in a database, or many other mechanisms.

This class is expected to be invoked via the concrete implementation of Lifecycle.

For the official specification for this class, see JSF Specification.

Version:

$Revision: 901847 $ $Date: 2010-01-21 15:30:23 -0500 (Thu, 21 Jan 2010) $

Author:

Manfred Geiler (latest modification by $Author: jakobk $)

Field Summary

static String	CHARACTER_ENCODING_KEY
static String	DEFAULT_FACELETS_SUFFIX
static String	DEFAULT_SUFFIX
static String	DEFAULT_SUFFIX_PARAM_NAME Indicate the default suffix to derive the file URI if extension mapping is used.
static String	FACELETS_SUFFIX_PARAM_NAME
static String	FACELETS_VIEW_MAPPINGS_PARAM_NAME

Constructor Summary

ViewHandler()

Method Summary

String	calculateCharacterEncoding(FacesContext context)
abstract Locale	calculateLocale(FacesContext context) Return the Locale object that should be used when rendering this view to the current user.
abstract String	calculateRenderKitId(FacesContext context) Return the id of an available render-kit that should be used to map the JSF components into user presentation.
abstract UIViewRoot	createView(FacesContext context, String viewId) Build a root node for a component tree.
String	deriveViewId(FacesContext context, String input)
abstract String	getActionURL(FacesContext context, String viewId) Returns a URL, suitable for encoding and rendering, that (if activated) will cause the JSF request processing lifecycle for the specified viewId to be executed
String	getBookmarkableURL(FacesContext context, String viewId, Map<String,List<String>> parameters, boolean includeViewParams) Return a JSF action URL derived from the viewId argument that is suitable to be used as the target of a link in a JSF response.
String	getRedirectURL(FacesContext context, String viewId, Map<String,List<String>> parameters, boolean includeViewParams) Return a JSF action URL derived from the viewId argument that is suitable to be used by the NavigationHandler to issue a redirect request to the URL using a NonFaces request.
abstract String	getResourceURL(FacesContext context, String path) Returns a URL, suitable for encoding and rendering, that (if activated) will retrieve the specified web application resource.
ViewDeclarationLanguage	getViewDeclarationLanguage(FacesContext context, String viewId) Return the ViewDeclarationLanguage instance used for this ViewHandler instance.
void	initView(FacesContext context) Initialize the view for the request processing lifecycle.
abstract void	renderView(FacesContext context, UIViewRoot viewToRender) Perform whatever actions are required to render the response view to the response object associated with the current FacesContext.
abstract UIViewRoot	restoreView(FacesContext context, String viewId) Perform whatever actions are required to restore the view associated with the specified FacesContext and viewId.
abstract void	writeState(FacesContext context) Take any appropriate action to either immediately write out the current state information (by calling StateManager.writeState(javax.faces.context.FacesContext, java.lang.Object), or noting where state information should later be written.

Methods inherited from class java.lang.Object

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

Field Detail

CHARACTER_ENCODING_KEY

public static final String CHARACTER_ENCODING_KEY

See Also:

Constant Field Values

DEFAULT_FACELETS_SUFFIX

public static final String DEFAULT_FACELETS_SUFFIX

See Also:

Constant Field Values

DEFAULT_SUFFIX

public static final String DEFAULT_SUFFIX

See Also:

Constant Field Values

DEFAULT_SUFFIX_PARAM_NAME

@JSFWebConfigParam(defaultValue=".xhtml .jsp",
                   since="1.1")
public static final String DEFAULT_SUFFIX_PARAM_NAME

Indicate the default suffix to derive the file URI if extension mapping is used.

See Also:

Constant Field Values

FACELETS_SUFFIX_PARAM_NAME

@JSFWebConfigParam(defaultValue=".xhtml",
                   since="2.0")
public static final String FACELETS_SUFFIX_PARAM_NAME

See Also:

Constant Field Values

FACELETS_VIEW_MAPPINGS_PARAM_NAME

@JSFWebConfigParam(since="2.0")
public static final String FACELETS_VIEW_MAPPINGS_PARAM_NAME

See Also:

Constant Field Values

Constructor Detail

ViewHandler

public ViewHandler()

Method Detail

calculateCharacterEncoding

public String calculateCharacterEncoding(FacesContext context)

Since:

JSF 1.2

calculateLocale

public abstract Locale calculateLocale(FacesContext context)

Return the Locale object that should be used when rendering this view to the current user.

Some request protocols allow an application user to specify what locale they prefer the response to be in. For example, HTTP requests can specify the "accept-language" header.

Method Application.getSupportedLocales() defines what locales this JSF application is capable of supporting.

This method should match such sources of data up and return the Locale object that is the best choice for rendering the current application to the current user.

calculateRenderKitId

public abstract String calculateRenderKitId(FacesContext context)

Return the id of an available render-kit that should be used to map the JSF components into user presentation.

The render-kit selected (eg html, xhtml, pdf, xul, ...) may depend upon the user, properties associated with the request, etc.

createView

public abstract UIViewRoot createView(FacesContext context,
                                      String viewId)

Build a root node for a component tree.

When a request is received, this method is called if restoreView returns null, ie this is not a "postback". In this case, a root node is created and then renderView is invoked. It is the responsibility of the renderView method to build the full component tree (ie populate the UIViewRoot with descendant nodes).

This method is also invoked when navigation occurs from one view to another, where the viewId passed is the id of the new view to be displayed. Again it is the responsibility of renderView to then populate the viewroot with descendants.

The locale and renderKit settings are inherited from the current UIViewRoot that is configured before this method is called. That means of course that they do NOT get set for GET requests, including navigation that has the redirect flag set.

deriveViewId

public String deriveViewId(FacesContext context,
                           String input)

Parameters:

context -

input -

Returns:

Since:

2.0

getActionURL

public abstract String getActionURL(FacesContext context,
                                    String viewId)

Returns a URL, suitable for encoding and rendering, that (if activated) will cause the JSF request processing lifecycle for the specified viewId to be executed

getBookmarkableURL

public String getBookmarkableURL(FacesContext context,
                                 String viewId,
                                 Map<String,List<String>> parameters,
                                 boolean includeViewParams)

Return a JSF action URL derived from the viewId argument that is suitable to be used as the target of a link in a JSF response. Compiliant implementations must implement this method as specified in section JSF.7.5.2. The default implementation simply calls through to getActionURL(javax.faces.context.FacesContext, java.lang.String), passing the arguments context and viewId.

Parameters:

context -

viewId -

parameters -

includeViewParams -

Returns:

Since:

2.0

getViewDeclarationLanguage

public ViewDeclarationLanguage getViewDeclarationLanguage(FacesContext context,
                                                          String viewId)

Return the ViewDeclarationLanguage instance used for this ViewHandler instance.

The default implementation of this method returns null.

Parameters:

context -

viewId -

Returns:

Since:

2.0

getRedirectURL

public String getRedirectURL(FacesContext context,
                             String viewId,
                             Map<String,List<String>> parameters,
                             boolean includeViewParams)

Return a JSF action URL derived from the viewId argument that is suitable to be used by the NavigationHandler to issue a redirect request to the URL using a NonFaces request. Compiliant implementations must implement this method as specified in section JSF.7.5.2. The default implementation simply calls through to getActionURL(javax.faces.context.FacesContext, java.lang.String), passing the arguments context and viewId.

Parameters:

context -

viewId -

parameters -

includeViewParams -

Returns:

Since:

2.0

getResourceURL

public abstract String getResourceURL(FacesContext context,
                                      String path)

Returns a URL, suitable for encoding and rendering, that (if activated) will retrieve the specified web application resource.

initView

public void initView(FacesContext context)
              throws FacesException

Initialize the view for the request processing lifecycle.

This method must be called at the beginning of the Restore View Phase of the Request Processing Lifecycle. It is responsible for performing any per-request initialization necessary to the operation of the lifycecle.

The default implementation must perform the following actions. If ExternalContext.getRequestCharacterEncoding() returns null, call calculateCharacterEncoding(javax.faces.context.FacesContext) and pass the result, if non-null, into the ExternalContext.setRequestCharacterEncoding(java.lang.String) method. If ExternalContext.getRequestCharacterEncoding() returns non-null take no action.

Throws:

FacesException

Since:

JSF 1.2

renderView

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

Perform whatever actions are required to render the response view to the response object associated with the current FacesContext.

Otherwise, the default implementation must obtain a reference to the ViewDeclarationLanguage for the viewId of the argument viewToRender and call its ViewDeclarationLanguage.renderView(javax.faces.context.FacesContext, javax.faces.component.UIViewRoot) method, returning the result and not swallowing any exceptions thrown by that method.

Throws:

IOException

FacesException

restoreView

public abstract UIViewRoot restoreView(FacesContext context,
                                       String viewId)

Perform whatever actions are required to restore the view associated with the specified FacesContext and viewId. It may delegate to the restoreView of the associated StateManager to do the actual work of restoring the view. If there is no available state for the specified viewId, return null.

Otherwise, the default implementation must obtain a reference to the ViewDeclarationLanguage for this viewId and call its ViewDeclarationLanguage.restoreView(javax.faces.context.FacesContext, java.lang.String) method, returning the result and not swallowing any exceptions thrown by that method.

writeState

public abstract void writeState(FacesContext context)
                         throws IOException

Take any appropriate action to either immediately write out the current state information (by calling StateManager.writeState(javax.faces.context.FacesContext, java.lang.Object), or noting where state information should later be written.

This method must do nothing if the current request is an Ajax request. When responding to Ajax requests, the state is obtained by calling StateManager.getViewState(javax.faces.context.FacesContext) and then written into the Ajax response during final encoding (UIViewRoot.encodeEnd(javax.faces.context.FacesContext).

Throws:

IOException