javax.faces.application.StateManager Maven / Gradle / Ivy
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* distributed with this work for additional information
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* 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 javax.faces.application;
/**
* 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 the javadoc for this class in the
* JSF Specification
* for more details.
*
* @author Manfred Geiler (latest modification by $Author: skitching $)
* @version $Revision: 705327 $ $Date: 2008-10-16 14:06:57 -0500 (Thu, 16 Oct 2008) $
*/
public abstract class StateManager
{
public static final String STATE_SAVING_METHOD_PARAM_NAME = "javax.faces.STATE_SAVING_METHOD";
public static final String STATE_SAVING_METHOD_CLIENT = "client";
public static final String STATE_SAVING_METHOD_SERVER = "server";
private Boolean _savingStateInClient = null;
/**
* Invokes getTreeStructureToSave and getComponentStateToSave, then return an object that wraps the two
* resulting objects. This object can then be passed to method writeState.
*/
public abstract StateManager.SerializedView saveSerializedView(javax.faces.context.FacesContext context);
/**
* Return data that is sufficient to recreate the component tree that is the viewroot of the specified
* context, but without restoring the state in the components.
*
* Using this data, a tree of components which has the same "shape" as the original component
* tree can be recreated. However the component instances themselves will have only their default
* values, ie their member fields will not have been set to the original values.
*/
protected abstract Object getTreeStructureToSave(javax.faces.context.FacesContext context);
/**
* Return data that can be applied to a component tree created using the "getTreeStructureToSave"
* method.
*/
protected abstract Object getComponentStateToSave(javax.faces.context.FacesContext context);
/**
* 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.
*/
public abstract void writeState(javax.faces.context.FacesContext context,
StateManager.SerializedView state)
throws java.io.IOException;
public abstract javax.faces.component.UIViewRoot restoreView(javax.faces.context.FacesContext context,
String viewId,
String renderKitId);
protected abstract javax.faces.component.UIViewRoot restoreTreeStructure(javax.faces.context.FacesContext context,
String viewId,
String renderKitId);
protected abstract void restoreComponentState(javax.faces.context.FacesContext context,
javax.faces.component.UIViewRoot viewRoot,
String renderKitId);
public boolean isSavingStateInClient(javax.faces.context.FacesContext context)
{
if(context == null) throw new NullPointerException("context");
if (_savingStateInClient != null) return _savingStateInClient.booleanValue();
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.equals(STATE_SAVING_METHOD_CLIENT))
{
_savingStateInClient = Boolean.TRUE;
}
else if (stateSavingMethod.equals(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.booleanValue();
}
public class SerializedView
{
private Object _structure;
private Object _state;
public SerializedView(Object structure, Object state)
{
_structure = structure;
_state = state;
}
public Object getStructure()
{
return _structure;
}
public Object getState()
{
return _state;
}
}
}