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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package jakarta.faces.application;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
import jakarta.faces.context.FacesContext;
import jakarta.faces.view.ViewDeclarationLanguage;
import java.io.IOException;
import java.util.Map;
import org.apache.myfaces.core.api.shared.lang.Assert;
/**
* 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 Faces 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 Faces components from the details of the request format. This class isolates
* Faces components from the details of the response format. Because request and response are typically tightly coupled,
* the StateManager and ViewHandler implementations are also typically fairly tightly coupled (ie the
* ViewHandler/StateManager implementations come as pairs).
*
* See also the Faces Specification
*/
public abstract class StateManager
{
/**
* 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.
*
*/
@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 = "jakarta.faces.STATE_SAVING_METHOD";
public static final String STATE_SAVING_METHOD_CLIENT = "client";
public static final String STATE_SAVING_METHOD_SERVER = "server";
/**
* Indicate the viewId(s) separated by commas that should be saved and restored fully,
* without use Partial State Saving (PSS).
*/
@JSFWebConfigParam(since="2.0", group="state")
public static final String FULL_STATE_SAVING_VIEW_IDS_PARAM_NAME = "jakarta.faces.FULL_STATE_SAVING_VIEW_IDS";
/**
* 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.
*/
@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 = "jakarta.faces.PARTIAL_STATE_SAVING";
private Boolean _savingStateInClient = null;
public static final String IS_BUILDING_INITIAL_STATE = "jakarta.faces.IS_BUILDING_INITIAL_STATE";
public static final String IS_SAVING_STATE = "jakarta.faces.IS_SAVING_STATE";
/**
* 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.
*
*/
@JSFWebConfigParam(since="2.2", group="state", tags="performance",
defaultValue="false", expectedValues="true,false")
public static final java.lang.String SERIALIZE_SERVER_STATE_PARAM_NAME = "jakarta.faces.SERIALIZE_SERVER_STATE";
/**
* 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.
*
* @since 2.0
* @param context
* @return
*/
public String getViewState(FacesContext context)
{
Object savedView = null;
if (context != null && !context.getViewRoot().isTransient())
{
String viewId = context.getViewRoot().getViewId();
ViewDeclarationLanguage vdl = context.getApplication().getViewHandler()
.getViewDeclarationLanguage(context, viewId);
if (vdl != null)
{
Map contextAttributes = context.getAttributes();
try
{
contextAttributes.put(IS_SAVING_STATE, Boolean.TRUE);
savedView = vdl.getStateManagementStrategy(context, viewId).saveView(context);
}
finally
{
contextAttributes.remove(IS_SAVING_STATE);
}
}
}
return context.getRenderKit().getResponseStateManager().getViewState(context, savedView);
}
public boolean isSavingStateInClient(FacesContext context)
{
Assert.notNull(context, "context");
if (_savingStateInClient != null)
{
return _savingStateInClient;
}
String stateSavingMethod = context.getExternalContext().getInitParameter(STATE_SAVING_METHOD_PARAM_NAME);
if (stateSavingMethod == null)
{
_savingStateInClient = Boolean.FALSE; // Specs 10.1.3: default server saving
context.getExternalContext().log("No state saving method defined, assuming default server state saving");
}
else if (stateSavingMethod.equalsIgnoreCase(STATE_SAVING_METHOD_CLIENT))
{
_savingStateInClient = Boolean.TRUE;
}
else if (stateSavingMethod.equalsIgnoreCase(STATE_SAVING_METHOD_SERVER))
{
_savingStateInClient = Boolean.FALSE;
}
else
{
_savingStateInClient = Boolean.FALSE; // Specs 10.1.3: default server saving
context.getExternalContext().log(
"Illegal state saving method '" + stateSavingMethod + "', default server state saving will be used");
}
return _savingStateInClient;
}
/**
* 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 Faces1.1 API
* to continue to work.
*
*
* @since 1.2
*/
public void writeState(FacesContext context, Object state) throws IOException
{
}
}