Package jakarta.faces.render

Class ResponseStateManager

  • public abstract class ResponseStateManager
extends Object

    ResponseStateManager is the helper class to StateManager that knows the specific rendering technology being used to generate the response. It is a singleton abstract class, vended by the RenderKit. This class knows the mechanics of saving state, whether it be in hidden fields, session, or some combination of the two.

    • Constructor Detail

      • ResponseStateManager

        public ResponseStateManager()

    • Method Detail

      • writeState

        public void writeState​(FacesContext context,
                       Object state)
                throws IOException

        Take the argument state and write it into the output using the current ResponseWriter, which must be correctly positioned already.

        Call FacesContext.getViewRoot(). If StateHolder.isTransient() returns true, take implementation specific action so that the following call to isStateless(jakarta.faces.context.FacesContext, java.lang.String) returns true and return. Otherwise, proceed as follows.

        If the state is to be written out to hidden fields, the implementation must take care to make all necessary character replacements to make the Strings suitable for inclusion as an HTTP request paramater.

        If the state saving method for this application is StateManager.STATE_SAVING_METHOD_CLIENT, the implementation must encrypt the state to be saved to the client in a tamper evident manner.

        If the state saving method for this application is StateManager.STATE_SAVING_METHOD_SERVER, and the current request is an Ajax request PartialViewContext.isAjaxRequest() returns true), use the current view state identifier if it is available (do not generate a new identifier).

        Write out the render kit identifier associated with this ResponseStateManager implementation with the name as the value of the String constant ResponseStateManager.RENDER_KIT_ID_PARAM. The render kit identifier must not be written if:

        The ClientWindow must be written using these steps. Call ExternalContext.getClientWindow(). If the result is null, take no further action regarding the ClientWindow. If the result is non-null, write a hidden field whose name is CLIENT_WINDOW_PARAM and whose id is <VIEW_ROOT_CONTAINER_CLIENT_ID><SEP>jakarta.faces.ClientWindow<SEP><UNIQUE_PER_VIEW_NUMBER> where <SEP> is the currently configured UINamingContainer.getSeparatorChar(). <VIEW_ROOT_CONTAINER_CLIENT_ID> is the return from UIViewRoot.getContainerClientId() on the view from whence this state originated. <UNIQUE_PER_VIEW_NUMBER> is a number that must be unique within this view, but must not be included in the view state. The value of the field is implementation dependent but must uniquely identify this window within the user's session.

        Parameters:
        context - The FacesContext instance for the current request
        state - The serialized state information previously saved
        Throws:
        IOException - if the state argument is not an array of length 2.
        Since:
        1.2

      • isStateless

        public boolean isStateless​(FacesContext context,
                           String viewId)

        If the preceding call to writeState(jakarta.faces.context.FacesContext, java.lang.Object) was stateless, return true. If the preceding call to writeState() was stateful, return false. Otherwise throw IllegalStateException.

        To preserve backward compatibility with custom implementations that may have extended from an earlier version of this class, an implementation is provided that returns false. A compliant implementation must override this method to take the specified action.

        Parameters:
        context - The FacesContext instance for the current request
        viewId - View identifier of the view to be restored
        Returns:
        the value of the statelessness of this run through the lifecycle.
        Throws:
        NullPointerException - if the argument context is null.
        IllegalStateException - if this method is invoked and the statefulness of the preceding call to writeState(jakarta.faces.context.FacesContext, java.lang.Object) cannot be determined.
        Since:
        2.2

      • getState

        public Object getState​(FacesContext context,
                       String viewId)

        The implementation must inspect the current request and return an Object representing the tree structure and component state passed in to a previous invocation of writeState(jakarta.faces.context.FacesContext,java.lang.Object).

        If the state saving method for this application is StateManager.STATE_SAVING_METHOD_CLIENT, writeState() will have encrypted the state in a tamper evident manner. If the state fails to decrypt, or decrypts but indicates evidence of tampering, a ProtectedViewException must be thrown.

        Parameters:
        context - The FacesContext instance for the current request
        viewId - View identifier of the view to be restored
        Returns:
        the tree structure and component state Object passed in to writeState. If this is an initial request, this method returns null.
        Since:
        1.2

      • isPostback

        public boolean isPostback​(FacesContext context)

        Return true if the current request is a postback. This method is leveraged from the Restore View Phase to determine if ViewHandler.restoreView(jakarta.faces.context.FacesContext, java.lang.String) or ViewHandler.createView(jakarta.faces.context.FacesContext, java.lang.String) should be called. The default implementation must return true if this ResponseStateManager instance wrote out state on a previous request to which this request is a postback, false otherwise.

        The implementation of this method for the Standard HTML RenderKit must consult the ExternalContext's requestParameterMap and return true if and only if there is a key equal to the value of the symbolic constant VIEW_STATE_PARAM.

        For backwards compatibility with implementations of ResponseStateManager prior to Jakarta Faces 1.2, a default implementation is provided that consults the ExternalContext's requestParameterMap and return true if its size is greater than 0.

        Parameters:
        context - the FacesContext for the current request.
        Returns:
        the value as specified above
        Since:
        1.2

      • getViewState

        public String getViewState​(FacesContext context,
                           Object state)

        Return the specified state as a String without any markup related to the rendering technology supported by this ResponseStateManager.

        Parameters:
        context - the FacesContext for the current request
        state - the state from which the String version will be generated from
        Returns:
        the view state for this request without any markup specifics
        Since:
        2.0

      • getCryptographicallyStrongTokenFromSession

        public String getCryptographicallyStrongTokenFromSession​(FacesContext context)

        Compliant implementations must return a cryptographically strong token for use to protect views in this application. For backwards compatibility with earlier revisions, a default implementation is provided that simply returns null.

        Parameters:
        context - the FacesContext for the current request
        Returns:
        a cryptographically strong value
        Since:
        2.2