StateManager (Java EE 5 SDK)

javax.faces.application Class StateManager

java.lang.Object
  javax.faces.application.StateManager

直接已知子类:

StateManagerWrapper

public abstract class StateManager

extends Object

StateManager directs the process of saving and restoring the view between requests. The StateManager instance for an application is retrieved from the Application instance, and thus cannot know any details of the markup language created by the RenderKit being used to render a view. The StateManager utilizes a helper object (ResponseStateManager), that is provided by the RenderKit implementation and is therefore aware of the markup language details.

STATE_SAVING_METHOD_PARAM_NAME

public static final String STATE_SAVING_METHOD_PARAM_NAME

The ServletContext init parameter consulted by the StateManager to tell where the state should be saved. Valid values are given as the values of the constants: STATE_SAVING_METHOD_CLIENT or STATE_SAVING_METHOD_SERVER.

If this parameter is not specified, the default value is the value of the constant STATE_SAVING_METHOD_CLIENT.

另请参见:

常量字段

STATE_SAVING_METHOD_CLIENT

public static final String STATE_SAVING_METHOD_CLIENT

Constant value for the initialization parameter named by the STATE_SAVING_METHOD_PARAM_NAME that indicates state saving should take place on the client.

另请参见:

常量字段

STATE_SAVING_METHOD_SERVER

public static final String STATE_SAVING_METHOD_SERVER

Constant value for the initialization parameter named by the STATE_SAVING_METHOD_PARAM_NAME that indicates state saving should take place on the server.

另请参见:

常量字段

StateManager

public StateManager()

saveSerializedView

public StateManager.SerializedView saveSerializedView(FacesContext context)

Deprecated. this has been replaced by saveView(javax.faces.context.FacesContext). The default implementation returns null.

Return the tree structure and component state information for the view contained in the specified FacesContext instance as an object of type StateManager.SerializedView. If there is no state information to be saved, return null instead.

Components may opt out of being included in the serialized view by setting their transient property to true. This must cause the component itself, as well as all of that component's children and facets, to be omitted from the saved tree structure and component state information.

This method must also enforce the rule that, for components with non-null ids, all components that are descendants of the same nearest NamingContainer must have unique identifiers.

参数:

context - FacesContext for the current request

抛出异常:

IllegalStateException - if more than one component or facet within the same NamingContainer in this view has the same non-null component id

saveView

public Object saveView(FacesContext context)

Return an opaque Object containing sufficient information for this same instance to restore the state of the current UIViewRoot on a subsequent request. The returned object must implement java.io.Serializable. If there is no state information to be saved, return null instead.

Components may opt out of being included in the serialized view by setting their transient property to true. This must cause the component itself, as well as all of that component's children and facets, to be omitted from the saved tree structure and component state information.

This method must also enforce the rule that, for components with non-null ids, all components that are descendants of the same nearest NamingContainer must have unique identifiers.

For backwards compatability with existing StateManager implementations, the default implementation of this method calls saveSerializedView(javax.faces.context.FacesContext) and creates and returns a two element Object array with element zero containing the structure property and element one containing the state property of the SerializedView.

参数:

context - FacesContext for the current request

抛出异常:

IllegalStateException - if more than one component or facet within the same NamingContainer in this view has the same non-null component id

从以下版本开始:

1.2

getTreeStructureToSave

protected Object getTreeStructureToSave(FacesContext context)

Deprecated. the distinction between tree structure and component state is now an implementation detail. The default implementation returns null.

Convenience method, which must be called by saveSerializedView(), to construct and return a Serializable object that represents the structure of the entire component tree (including children and facets) of this view.

Components may opt-out of being included in the tree structure by setting their transient property to true. This must cause the component itself, as well as all of that component's children and facets, to be omitted from the saved tree structure information.

参数:

context - FacesContext for the current request

getComponentStateToSave

protected Object getComponentStateToSave(FacesContext context)

Deprecated. the distinction between tree structure and component state is now an implementation detail. The default implementation returns null.

Convenience method, which must be called by saveSerializedView(), to construct and return a Serializable object that represents the state of all component properties, attributes, and attached objects, for the entire component tree (including children and facets) of this view.

Components may opt-out of being included in the component state by setting their transient property to true. This must cause the component itself, as well as all of that component's children and facets, to be omitted from the saved component state information.

参数:

context - FacesContext for the current request

writeState

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

Save the state represented in the specified state Object instance, in an implementation dependent manner.

This method will typically simply delegate the actual writing to the writeState() method of the ResponseStateManager instance provided by the RenderKit being used to render this view. This method assumes that the caller has positioned the ResponseWriter at the correct position for the saved state to be written.

For backwards compatability with existing StateManager implementations, the default implementation of this method checks if the argument is an instance of Object [] of length greater than or equal to two. If so, it creates a SerializedView instance with the tree structure coming from element zero and the component state coming from element one and calls through to writeState(javax.faces.context.FacesContext,javax.faces.application.StateManager.SerializedView). If not, does nothing.

参数:

context - FacesContext for the current request

state - the Serializable state to be written, as returned by saveSerializedView(javax.faces.context.FacesContext)

抛出异常:

IOException

从以下版本开始:

1.2

writeState

public void writeState(FacesContext context,
                       StateManager.SerializedView state)
                throws IOException

Deprecated. This method has been replaced by writeState(javax.faces.context.FacesContext,java.lang.Object). The default implementation of this method does nothing.

Save the state represented in the specified SerializedView isntance, in an implementation dependent manner.

This method must consult the context initialization parameter named by the symbolic constant StateManager.STATE_SAVING_METHOD_PARAMETER_NAME to determine whether state should be saved on the client or the server. If not present, client side state saving is assumed.

If the init parameter indicates that client side state saving should be used, this method must delegate the actual writing to the writeState() method of the ResponseStateManager instance provided by the RenderKit being used to render this view. This method assumes that the caller has positioned the ResponseWriter at the correct position for the saved state to be written.

参数:

context - FacesContext for the current request

state - the serialized state to be written

抛出异常:

IOException

restoreView

public abstract UIViewRoot restoreView(FacesContext context,
                                       String viewId,
                                       String renderKitId)

Restore the tree structure and the component state of the view for the specified viewId, in an implementation dependent manner, and return the restored UIViewRoot. If there is no saved state information available for this viewId, return null instead.

This method must consult the context initialization parameter named by the symbolic constant StateManager.STATE_SAVING_METHOD_PARAMETER_NAME to determine whether state should be saved on the client or the server. If not present, client side state saving is assumed.

If the init parameter indicates that client side state saving should be used, this method must call the getTreeStructureToRestore() and (if the previous method call returned a non-null value) getComponentStateToRestore() methods of the ResponseStateManager instance provided by the RenderKit responsible for this view.

参数:

context - FacesContext for the current request

viewId - View identifier of the view to be restored

renderKitId - the renderKitId used to render this response. Must not be null.

抛出异常:

IllegalArgumentException - if renderKitId is null.

restoreTreeStructure

protected UIViewRoot restoreTreeStructure(FacesContext context,
                                          String viewId,
                                          String renderKitId)

Deprecated. the distinction between tree structure and component state is now an implementation detail. The default implementation returns null.

Convenience method, which must be called by restoreView(), to construct and return a UIViewRoot instance (populated with children and facets) representing the tree structure of the component tree being restored. If no saved state information is available, return null instead.

参数:

context - FacesContext for the current request

viewId - View identifier of the view to be restored

renderKitId - the renderKitId used to render this response. Must not be null.

抛出异常:

IllegalArgumentException - if renderKitId is null.

restoreComponentState

protected void restoreComponentState(FacesContext context,
                                     UIViewRoot viewRoot,
                                     String renderKitId)

Deprecated. the distinction between tree structure and component state is now an implementation detail. The default implementation does nothing.

Convenience method, which must be called by restoreView(), to restore the attributes, properties, and attached objects of all components in the restored component tree.

参数:

context - FacesContext for the current request

viewRoot - UIViewRoot returned by a previous call to restoreTreeStructure()

renderKitId - the renderKitId used to render this response. Must not be null.

抛出异常:

IllegalArgumentException - if renderKitId is null.

isSavingStateInClient

public boolean isSavingStateInClient(FacesContext context)

返回:

true if and only if the value of the ServletContext init parameter named by the value of the constant STATE_SAVING_METHOD_PARAM_NAME is equal to the value of the constant STATE_SAVING_METHOD_CLIENT. false otherwise.

抛出异常:

NullPointerException - if context is null.

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