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package com.sun.faces.context;
import com.sun.faces.RIConstants;
import com.sun.faces.application.ApplicationAssociate;
import com.sun.faces.application.ApplicationStateInfo;
import com.sun.faces.util.ComponentStruct;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.event.AbortProcessingException;
import javax.faces.event.PostAddToViewEvent;
import javax.faces.event.PreRemoveFromViewEvent;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.HashMap;
import static com.sun.faces.RIConstants.DYNAMIC_CHILD_COUNT;
import static com.sun.faces.RIConstants.DYNAMIC_COMPONENT;
import javax.faces.FacesException;
/**
* Context for dealing with partial state saving mechanics.
*/
public class StateContext {
private static final String KEY = StateContext.class.getName() + "_KEY";
private boolean partial;
private boolean partialLocked;
private boolean trackMods = true;
private AddRemoveListener modListener;
private ApplicationStateInfo stateInfo;
private WeakReference<UIViewRoot> viewRootRef = new WeakReference<UIViewRoot>(null);
// ------------------------------------------------------------ Constructors
private StateContext(ApplicationStateInfo stateInfo) {
this.stateInfo = stateInfo;
}
// ---------------------------------------------------------- Public Methods
/**
* @param ctx the <code>FacesContext</code> for the current request
* @return <code>StateContext</code> for this request
*/
public static StateContext getStateContext(FacesContext ctx) {
StateContext stateCtx = (StateContext) ctx.getAttributes().get(KEY);
if (stateCtx == null) {
ApplicationAssociate associate = ApplicationAssociate.getCurrentInstance();
ApplicationStateInfo info = associate.getApplicationStateInfo();
stateCtx = new StateContext(info);
ctx.getAttributes().put(KEY, stateCtx);
}
return stateCtx;
}
/**
* @param ctx FacesContext.
* @param viewId the view ID to check or null if viewId is unknown.
* @return <code>true</code> if partial state saving should be used for the
* specified view ID, otherwise <code>false</code>
*/
public boolean isPartialStateSaving(FacesContext ctx, String viewId) {
// track UIViewRoot changes
UIViewRoot root = ctx.getViewRoot();
UIViewRoot refRoot = viewRootRef.get();
if (root != refRoot) {
// set weak reference to current viewRoot
this.viewRootRef = new WeakReference<UIViewRoot>(root);
// On first call in restore phase, viewRoot is null, so we treat the first
// change to not null not as a changing viewRoot.
if (refRoot != null) {
// view root changed in request processing - force usage of a
// new AddRemoveListener instance for the new viewId ...
modListener = null;
// ... and also force check for partial state saving for the new viewId
partialLocked = false;
}
}
if (!partialLocked) {
if (viewId == null) {
if (root != null) {
viewId = root.getViewId();
} else {
// View root has not yet been initialized. Check to see whether
// the target view id has been stashed away for us.
viewId = (String)ctx.getAttributes().get(RIConstants.VIEWID_KEY_NAME);
}
}
partial = stateInfo.usePartialStateSaving(viewId);
partialLocked = true;
}
return partial;
}
/**
* @return <code>true</code> if view modifications outside of the initial
* construction of the view are being tracked.
*/
public boolean trackViewModifications() {
return trackMods;
}
/**
* Installs a <code>SystemEventListener</code> on the <code>UIViewRoot</code>
* to track components added to or removed from the view.
*/
public void startTrackViewModifications(FacesContext ctx, UIViewRoot root) {
if (modListener == null) {
modListener = new AddRemoveListener(ctx);
root.subscribeToViewEvent(PostAddToViewEvent.class, modListener);
root.subscribeToViewEvent(PreRemoveFromViewEvent.class, modListener);
}
setTrackViewModifications(true);
}
/**
* Toggles the current modification tracking status.
*
* @param trackMods if <code>true</code> and the listener installed by
* {@link #startTrackViewModifications(javax.faces.context.FacesContext, javax.faces.component.UIViewRoot)
* is present, then view modifications will be tracked. If
* <code>false</code>, then modification events will be ignored.
*/
public void setTrackViewModifications(boolean trackMods) {
this.trackMods = trackMods;
}
/**
* @param c the UIComponent to check
* @return <code>true</code> if the component was added after the initial
* view construction
*/
public boolean componentAddedDynamically(UIComponent c) {
return c.getAttributes().containsKey(DYNAMIC_COMPONENT);
}
public int getIndexOfDynamicallyAddedChildInParent(UIComponent c) {
int result = -1;
Map<String, Object> attrs = c.getAttributes();
if (attrs.containsKey(DYNAMIC_COMPONENT)) {
result = (Integer) attrs.get(DYNAMIC_COMPONENT);
}
return result;
}
public boolean hasOneOrMoreDynamicChild(UIComponent parent) {
return parent.getAttributes().containsKey(DYNAMIC_CHILD_COUNT);
}
private int incrementDynamicChildCount(UIComponent parent) {
int result = 0;
Map<String, Object> attrs = parent.getAttributes();
Integer cur = (Integer) attrs.get(DYNAMIC_CHILD_COUNT);
if (null != cur) {
result = cur++;
} else {
result = 1;
}
attrs.put(DYNAMIC_CHILD_COUNT, (Integer) result);
return result;
}
private int decrementDynamicChildCount(UIComponent parent) {
int result = 0;
Map<String, Object> attrs = parent.getAttributes();
Integer cur = (Integer) attrs.get(DYNAMIC_CHILD_COUNT);
if (null != cur) {
result = (0 < cur) ? cur-- : 0;
}
if (0 == result && null != cur){
attrs.remove(DYNAMIC_CHILD_COUNT);
}
return result;
}
/**
* Get the dynamic list (of adds and removes).
*/
public List<ComponentStruct> getDynamicActions() {
return ((modListener != null) ? modListener.getDynamicActions() : null);
}
/**
* Get the hash map of dynamic components.
*
* @return the hash map of dynamic components.
*/
public HashMap<String, UIComponent> getDynamicComponents() {
return ((modListener != null) ? modListener.getDynamicComponents() : null);
}
// ---------------------------------------------------------- Nested Classes
/**
* A system event listener which is used to listen for changes on the
* component tree after restore view and before rendering out the view.
*/
public class AddRemoveListener implements SystemEventListener {
/**
* Stores the state context we work for,
*/
private StateContext stateCtx;
/**
* Stores the list of adds/removes.
*/
private List<ComponentStruct> dynamicActions;
/**
* Stores the hash map of dynamic components.
*/
private transient HashMap<String, UIComponent> dynamicComponents;
/**
* Constructor.
*
* @param context the Faces context.
*/
public AddRemoveListener(FacesContext context) {
stateCtx = StateContext.getStateContext(context);
}
/**
* Get the list of adds/removes.
*
* @return the list of adds/removes.
*/
public List<ComponentStruct> getDynamicActions() {
synchronized(this) {
if (dynamicActions == null) {
dynamicActions = new ArrayList<ComponentStruct>();
}
}
return dynamicActions;
}
/**
* Get the hash map of dynamic components.
*
* @return the hash map of dynamic components.
*/
public HashMap<String, UIComponent> getDynamicComponents() {
synchronized(this) {
if (dynamicComponents == null) {
dynamicComponents = new HashMap<String, UIComponent>();
}
}
return dynamicComponents;
}
/**
* Process the add/remove event.
*
* @param event the add/remove event.
* @throws AbortProcessingException when processing should be aborted.
*/
public void processEvent(SystemEvent event)
throws AbortProcessingException {
FacesContext ctx = FacesContext.getCurrentInstance();
if (event instanceof PreRemoveFromViewEvent) {
if (stateCtx.trackViewModifications()) {
handleRemove(ctx, ((PreRemoveFromViewEvent) event).getComponent());
}
} else {
if (stateCtx.trackViewModifications()) {
handleAdd(ctx, ((PostAddToViewEvent) event).getComponent());
}
}
}
/**
* Are we listening for these particular changes.
*
* <p>
* Note we are only interested in UIComponent adds/removes that are
* not the UIViewRoot itself.
* </p>
*
* @param source the source object we might be listening for.
* @return true if the source is OK, false otherwise.
*/
public boolean isListenerForSource(Object source) {
return (source instanceof UIComponent && !(source instanceof UIViewRoot));
}
/**
* Handle the remove.
*
* @param context the Faces context.
* @param component the UI component to add to the list as a REMOVE.
*/
private void handleRemove(FacesContext context, UIComponent component) {
if (!component.isTransient() && !hasTransientAncestor(component)) {
if (component.isInView()) {
decrementDynamicChildCount(component.getParent());
ComponentStruct struct = new ComponentStruct();
struct.action = ComponentStruct.REMOVE;
struct.clientId = component.getClientId(context);
struct.id = component.getId();
handleAddRemoveWithAutoPrune(component, struct);
}
}
}
/**
* Handle the add.
*
* @param context the Faces context.
* @param component the UI component to add to the list as an ADD.
*/
private void handleAdd(FacesContext context, UIComponent component) {
if (!component.isTransient() && !hasTransientAncestor(component)) {
if (component.getParent() != null && component.getParent().isInView()) {
String id = component.getId();
/*
* Since adding a component, can mean you are really reparenting
* it, we need to make sure the OLD clientId is not cached, we do
* that by setting the id.
*/
if (id != null) {
component.setId(id);
}
if (component.getParent().getFacets().containsValue(component)) {
Map facets = component.getParent().getFacets();
Iterator entries = facets.entrySet().iterator();
while (entries.hasNext()) {
Map.Entry entry = (Map.Entry) entries.next();
if (entry.getValue() == component) {
incrementDynamicChildCount(component.getParent());
component.clearInitialState();
component.getAttributes().put(DYNAMIC_COMPONENT, component.getParent().getChildren().indexOf(component));
ComponentStruct struct = new ComponentStruct();
struct.action = ComponentStruct.ADD;
struct.facetName = entry.getKey().toString();
struct.parentClientId = component.getParent().getClientId(context);
struct.clientId = component.getClientId(context);
struct.id = component.getId();
handleAddRemoveWithAutoPrune(component, struct);
}
}
}
else {
incrementDynamicChildCount(component.getParent());
component.clearInitialState();
component.getAttributes().put(DYNAMIC_COMPONENT, component.getParent().getChildren().indexOf(component));
ComponentStruct struct = new ComponentStruct();
struct.action = ComponentStruct.ADD;
struct.parentClientId = component.getParent().getClientId(context);
struct.clientId = component.getClientId(context);
struct.id = component.getId();
handleAddRemoveWithAutoPrune(component, struct);
}
}
}
}
/**
* Methods that takes care of pruning and adding an action to the
* dynamic action list.
*
* <pre>
* If you add a component and the dynamic action list does not contain
* the component yet then add it to the dynamic action list, regardless
* whether or not if was an ADD or REMOVE.
* </pre>
*
* <pre>
* Else if you add a component and it is already in the dynamic action
* list and it is the only action for that client id in the dynamic
* action list then:
* 1) If the previous action was an ADD then
* a) If the current action is a REMOVE then remove the component
* out of the dynamic action list.
* b) If the current action is an ADD then throw a FacesException.
* 2) If the previous action was a REMOVE then
* a) If the current action is an ADD then add it to the dynamic
* action list.
* b) If the current action is a REMOVE then throw a FacesException.
* </pre>
*
* <pre>
* Else if a REMOVE and ADD where captured before then:
* 1) If the current action is REMOVE then remove the last dynamic
* action out of the dynamic action list.
* 2) If the current action is ADD then throw a FacesException.
* </pre>
*
* @param component the UI component.
* @param struct the dynamic action.
*/
private void handleAddRemoveWithAutoPrune(UIComponent component, ComponentStruct struct) {
List<ComponentStruct> actionList = getDynamicActions();
HashMap<String, UIComponent> componentMap = getDynamicComponents();
int firstIndex = actionList.indexOf(struct);
if (firstIndex == -1) {
actionList.add(struct);
componentMap.put(struct.clientId, component);
} else {
int lastIndex = actionList.lastIndexOf(struct);
if (lastIndex == firstIndex) {
ComponentStruct previousStruct = actionList.get(firstIndex);
if (ComponentStruct.ADD.equals(previousStruct.action)) {
if (ComponentStruct.ADD.equals(struct.action)) {
throw new FacesException("Cannot add the same component twice: " + struct.clientId);
}
if (ComponentStruct.REMOVE.equals(struct.action)) {
actionList.remove(firstIndex);
componentMap.remove(struct.clientId);
}
}
if (ComponentStruct.REMOVE.equals(previousStruct.action)) {
if (ComponentStruct.ADD.equals(struct.action)) {
actionList.add(struct);
componentMap.put(struct.clientId, component);
}
if (ComponentStruct.REMOVE.equals(struct.action)) {
throw new FacesException("Cannot remove the same component twice: " + struct.clientId);
}
}
} else {
if (ComponentStruct.ADD.equals(struct.action)) {
throw new FacesException("Cannot add the same component twice: " + struct.clientId);
}
if (ComponentStruct.REMOVE.equals(struct.action)) {
actionList.remove(lastIndex);
}
}
}
}
private boolean hasTransientAncestor(UIComponent component) {
UIComponent parent = component.getParent();
while (parent != null) {
if (parent.isTransient()) {
return true;
}
parent = parent.getParent();
}
return false;
}
} // END AddRemoveListener
} // END StateContext