javax.faces.application.StateManager Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* 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;
import javax.faces.context.FacesContext;
import org.apache.myfaces.buildtools.maven2.plugin.builder.annotation.JSFWebConfigParam;
import java.io.IOException;
/**
* 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
*
* @author Manfred Geiler (latest modification by $Author: lu4242 $)
* @author Stan Silvert
* @version $Revision: 833810 $ $Date: 2009-11-07 21:40:01 -0500 (Sat, 07 Nov 2009) $
*/
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")
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.
*
* Deprecated; use saveView instead.
*
* @deprecated
*/
public StateManager.SerializedView saveSerializedView(javax.faces.context.FacesContext context) {
return null;
}
/**
* Returns an object that is sufficient to recreate the component tree that is the viewroot of
* the specified context.
*
* The return value is suitable for passing to method writeState.
*
* @since 1.2
*/
public Object saveView(FacesContext context) {
StateManager.SerializedView serializedView = saveSerializedView(context);
if (serializedView == null) return null;
Object[] structureAndState = new Object[2];
structureAndState[0] = serializedView.getStructure();
structureAndState[1] = serializedView.getState();
return structureAndState;
}
/**
* 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.
*
* Deprecated; use saveView instead.
*
* @deprecated
*/
protected Object getTreeStructureToSave(javax.faces.context.FacesContext context) {
return null;
}
/**
* Return data that can be applied to a component tree created using the "getTreeStructureToSave"
* method.
*
* Deprecated; use saveView instead.
*
* @deprecated
*/
protected Object getComponentStateToSave(javax.faces.context.FacesContext context) {
return null;
}
/**
* 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.
*
* Deprecated; use writeState(FacesContext, Object) instead. This method was abstract
* in JSF1.1, but is now an empty non-abstract method so that old classes that implement
* this method continue to work, while new classes can just override the new writeState
* method rather than this one.
*
* @deprecated
*/
public void writeState(javax.faces.context.FacesContext context,
StateManager.SerializedView state)
throws java.io.IOException {
// default impl does nothing as per JSF 1.2 javadoc
}
/**
* 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.
*
* @since 1.2
*/
public void writeState(FacesContext context, Object state) throws IOException {
if (!(state instanceof Object[])) return;
Object[] structureAndState = (Object[])state;
if (structureAndState.length < 2) return;
writeState(context, new StateManager.SerializedView(structureAndState[0], structureAndState[1]));
}
public abstract javax.faces.component.UIViewRoot restoreView(javax.faces.context.FacesContext context,
String viewId,
String renderKitId);
/**
* @deprecated
*/
protected javax.faces.component.UIViewRoot restoreTreeStructure(javax.faces.context.FacesContext context,
String viewId,
String renderKitId) {
return null;
}
/**
* @deprecated
*/
protected void restoreComponentState(javax.faces.context.FacesContext context,
javax.faces.component.UIViewRoot viewRoot,
String renderKitId) {
// default impl does nothing as per JSF 1.2 javadoc
}
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();
}
/**
* @deprecated
*/
public class SerializedView
{
private Object _structure;
private Object _state;
/**
* @deprecated
*/
public SerializedView(Object structure, Object state)
{
_structure = structure;
_state = state;
}
/**
* @deprecated
*/
public Object getStructure()
{
return _structure;
}
/**
* @deprecated
*/
public Object getState()
{
return _state;
}
}
}