Class ViewHandler

java.lang.Object
jakarta.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 jakarta.servlet apis. This allows Faces to be used on servers that do not implement the servlet API (for example, plain CGI).

Examples:

  • 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 Faces Specification.

  • Field Details

    • CHARACTER_ENCODING_KEY

      public static final String CHARACTER_ENCODING_KEY
      See Also:
    • DEFAULT_FACELETS_SUFFIX

      public static final String DEFAULT_FACELETS_SUFFIX
      See Also:
    • DEFAULT_SUFFIX

      @Deprecated(since="4.0") public static final String DEFAULT_SUFFIX
      Deprecated.
      See Also:
    • DEFAULT_SUFFIX_PARAM_NAME

      @JSFWebConfigParam(defaultValue=".xhtml", since="1.1", group="viewhandler", deprecated=true) @Deprecated(since="4.0") public static final String DEFAULT_SUFFIX_PARAM_NAME
      Deprecated.
      Indicate the default suffixes, separated by spaces to derive the default file URI used by Faces to create views and render pages.
      See Also:
    • FACELETS_SUFFIX_PARAM_NAME

      @JSFWebConfigParam(defaultValue=".xhtml", since="2.0", group="viewhandler") public static final String FACELETS_SUFFIX_PARAM_NAME
      The default extension used to handle facelets pages.
      See Also:
    • FACELETS_VIEW_MAPPINGS_PARAM_NAME

      @JSFWebConfigParam(since="2.0", group="viewhandler") public static final String FACELETS_VIEW_MAPPINGS_PARAM_NAME
      Set of extensions handled by facelets, separated by ';'.
      See Also:
    • FACELETS_BUFFER_SIZE_PARAM_NAME

      @JSFWebConfigParam(since="2.0", alias="facelets.BUFFER_SIZE", classType="java.lang.Integer", tags="performance", defaultValue="1024", desc="Define the default buffer size value passed to ExternalContext.setResponseBufferResponse() and in a servlet environment to HttpServletResponse.setBufferSize()") public static final String FACELETS_BUFFER_SIZE_PARAM_NAME
      Define the default buffer size value passed to ExternalContext.setResponseBufferResponse() and in a servlet environment to HttpServletResponse.setBufferSize().
      See Also:
    • FACELETS_DECORATORS_PARAM_NAME

      @JSFWebConfigParam(since="2.0", alias="facelets.DECORATORS") public static final String FACELETS_DECORATORS_PARAM_NAME
      Set of class names, separated by ';', implementing TagDecorator interface, used to transform a view definition in a facelet abstract syntax tree, that is used later to generate a component tree.
      See Also:
    • FACELETS_LIBRARIES_PARAM_NAME

      @JSFWebConfigParam(since="2.0", desc="Set of .taglib.xml files, separated by \';\' that should be loaded by facelet engine.", alias="facelets.LIBRARIES") public static final String FACELETS_LIBRARIES_PARAM_NAME
      Set of .taglib.xml files, separated by ';' that should be loaded by facelet engine.
      See Also:
    • FACELETS_REFRESH_PERIOD_PARAM_NAME

      @JSFWebConfigParam(since="2.0", defaultValue="0, -1 in Production", alias="facelets.REFRESH_PERIOD", classType="java.lang.Long", tags="performance") public static final String FACELETS_REFRESH_PERIOD_PARAM_NAME
      Define the period used to refresh the facelet abstract syntax tree from the view definition file.
      See Also:
    • FACELETS_SKIP_COMMENTS_PARAM_NAME

      @JSFWebConfigParam(since="2.0", alias="facelets.SKIP_COMMENTS") public static final String FACELETS_SKIP_COMMENTS_PARAM_NAME
      Skip comments found on a facelet file.
      See Also:
  • Constructor Details

    • ViewHandler

      public ViewHandler()
  • Method Details

    • calculateCharacterEncoding

      public String calculateCharacterEncoding(FacesContext context)
      Since:
      Faces 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 Faces 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 Faces 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
    • deriveLogicalViewId

      public String deriveLogicalViewId(FacesContext context, String rawViewId)
      Parameters:
      context -
      rawViewId -
      Returns:
      Since:
      2.1
    • getActionURL

      public abstract String getActionURL(FacesContext context, String viewId)
      Returns a URL, suitable for encoding and rendering, that (if activated) will cause the Faces 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 Faces action URL derived from the viewId argument that is suitable to be used as the target of a link in a Faces response. Compiliant implementations must implement this method as specified in section Faces.7.5.2. The default implementation simply calls through to getActionURL(jakarta.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 Faces 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 Faces.7.5.2. The default implementation simply calls through to getActionURL(jakarta.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(jakarta.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:
      Faces 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(jakarta.faces.context.FacesContext, jakarta.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(jakarta.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(jakarta.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(jakarta.faces.context.FacesContext) and then written into the Ajax response during final encoding (UIViewRoot.encodeEnd(jakarta.faces.context.FacesContext).

      Throws:
      IOException
    • addProtectedView

      public void addProtectedView(String urlPattern)
      Parameters:
      urlPattern -
      Since:
      2.2
    • removeProtectedView

      public boolean removeProtectedView(String urlPattern)
      Parameters:
      urlPattern -
      Since:
      2.2
    • getProtectedViewsUnmodifiable

      public Set<String> getProtectedViewsUnmodifiable()
      Returns:
      Since:
      2.2
    • getWebsocketURL

      public abstract String getWebsocketURL(FacesContext context, String channelAndToken)
      Return a Faces URL that represents a websocket connection for the passed channel and channelToken
      Parameters:
      context -
      channelAndToken -
      Returns:
      Since:
      2.3
    • getViews

      public Stream<String> getViews(FacesContext facesContext, String path, ViewVisitOption... options)
      Parameters:
      facesContext -
      path -
      options -
      Returns:
      Since:
      2.3
    • getViews

      public Stream<String> getViews(FacesContext facesContext, String path, int maxDepth, ViewVisitOption... options)
      Parameters:
      facesContext -
      path -
      maxDepth -
      options -
      Returns:
      Since:
      2.3