Package jakarta.faces.application

Class StateManager

  • Direct Known Subclasses:
    StateManagerWrapper
    public abstract class StateManager
extends Object
    Responsible for storing sufficient information about a component tree so that an identical tree can later be recreated.

    It is up to the concrete implementation to decide whether to use information from the "view template" that was used to first create the view, or whether to store sufficient information to enable the view to be restored without any reference to the original template. However as JSF components have mutable fields that can be set by code, and affected by user input, at least some state does need to be kept in order to recreate a previously-existing component tree.

    There are two different options defined by the specification: "client" and "server" state.

    When "client" state is configured, all state information required to create the tree is embedded within the data rendered to the client. Note that because data received from a remote client must always be treated as "tainted", care must be taken when using such data. Some StateManager implementations may use encryption to ensure that clients cannot modify the data, and that the data received on postback is therefore trustworthy.

    When "server" state is configured, the data is saved somewhere "on the back end", and (at most) a token is embedded in the data rendered to the user.

    This class is usually invoked by a concrete implementation of ViewHandler.

    Note that class ViewHandler isolates JSF components from the details of the request format. This class isolates JSF components from the details of the response format. Because request and response are usually tightly coupled, the StateManager and ViewHandler implementations are also usually fairly tightly coupled (ie the ViewHandler/StateManager implementations come as pairs).

    See also the JSF Specification

    • Field Detail

      • STATE_SAVING_METHOD_PARAM_NAME

        @JSFWebConfigParam(defaultValue="server",
                   expectedValues="server,client",
                   since="1.1",
                   group="state",
                   tags="performance",
                   ignoreUpperLowerCase=true,
                   desc="Define the state method to be used. There are two different options defined by the specification: \'client\' and \'server\' state.")
public static final String STATE_SAVING_METHOD_PARAM_NAME
        Define the state method to be used. There are two different options defined by the specification: "client" and "server" state.

        When "client" state is configured, all state information required to create the tree is embedded within the data rendered to the client. Note that because data received from a remote client must always be treated as "tainted", care must be taken when using such data. Some StateManager implementations may use encryption to ensure that clients cannot modify the data, and that the data received on postback is therefore trustworthy.

        When "server" state is configured, the data is saved somewhere "on the back end", and (at most) a token is embedded in the data rendered to the user.

        See Also:
        Constant Field Values

      • FULL_STATE_SAVING_VIEW_IDS_PARAM_NAME

        @JSFWebConfigParam(since="2.0",
                   group="state")
public static final String FULL_STATE_SAVING_VIEW_IDS_PARAM_NAME
        Indicate the viewId(s) separated by commas that should be saved and restored fully, without use Partial State Saving (PSS).
        See Also:
        Constant Field Values

      • PARTIAL_STATE_SAVING_PARAM_NAME

        @JSFWebConfigParam(expectedValues="true,false",
                   since="2.0",
                   defaultValue="true (false with 1.2 webapps)",
                   tags="performance",
                   group="state")
public static final String PARTIAL_STATE_SAVING_PARAM_NAME
        Enable or disable partial state saving algorithm.

        Partial State Saving algorithm allows to reduce the size of the state required to save a view, keeping track of the "delta" or differences between the view build by first time and the current state of the view.

        If the webapp faces-config file version is 2.0 or upper the default value is true, otherwise is false.

        See Also:
        Constant Field Values

      • SERIALIZE_SERVER_STATE_PARAM_NAME

        @JSFWebConfigParam(since="2.2",
                   group="state",
                   tags="performance",
                   defaultValue="false",
                   expectedValues="true,false")
public static final String SERIALIZE_SERVER_STATE_PARAM_NAME
        Indicate if the state should be serialized before save it on the session.

        Only applicable if state saving method is "server" (= default). If true (default) the state will be serialized to a byte stream before it is written to the session. If false the state will not be serialized to a byte stream.

        See Also:
        Constant Field Values

    • Constructor Detail

      • StateManager

        public StateManager()

    • Method Detail

      • getViewState

        public String getViewState​(FacesContext context)
        This method should be called from somewhere when ajax response is created to update the state saving param on client. The place where this method is called is an implementation detail, so there is no references about from where in the spec javadoc.
        Parameters:
        context -
        Returns:
        Since:
        2.0

      • isSavingStateInClient

        public boolean isSavingStateInClient​(FacesContext context)

      • writeState

        public void writeState​(FacesContext context,
                       Object state)
                throws IOException
        Associate the provided state object with the current response being generated.

        When client-side state is enabled, it is expected that method writes the data contained in the state parameter to the response somehow.

        When server-side state is enabled, at most a "token" is expected to be written.

        This method should be overridden by subclasses. It is not abstract because a default implementation is provided that forwards to the old writeState method; this allows subclasses of StateManager written using the JSF1.1 API to continue to work.

        Throws:
        IOException
        Since:
        1.2