org.apache.tapestry5.internal.structure
Interface Page

All Superinterfaces:

PageLifecycleCallbackHub

All Known Implementing Classes:

PageImpl

public interface Page
extends PageLifecycleCallbackHub

Represents a unique page within the application. Pages are part of the internal structure of a Tapestry application; end developers who refer to "page" are really referring to the root component of the actual page.

Starting in release 5.2, the nature of pages changed considerably. Pages are no longer pooled instances. Instead, pages are shared instances (per locale) but all internal mutable state is stored inside PerthreadManager. Page construction time is considered to extend past the page loaded callback. This is not quite perfect from a threading point-of-view (arguably, even write-once-read-many fields should be protected by synchronized blocks or other mechanisms). At best, we can be assured that the entire page construction phase is protected by a single synchronized block (but not on the page itself). An ideal system would build the page bottom to top so that all assignments could take place in constructors, assigning to final fields. Maybe some day.

The Page object is never visible to end-user code, though it exposes an interface (PageLifecycleCallbackHub that is).

Nested Class Summary

static class

Page.Stats Page construction statistics for the page.

Method Summary

void	addLifecycleListener(PageLifecycleListener listener) Deprecated. in 5.3.4; use PageLifecycleCallbackHub.addPageLoadedCallback(Runnable), PageLifecycleCallbackHub.addPageAttachedCallback(Runnable), or PageLifecycleCallbackHub.addPageDetachedCallback(Runnable) instead
void	addResetListener(PageResetListener listener) Deprecated. in 5.3.4,
void	attached() Invoked to inform the page that it is attached to the current request.
boolean	detached() Invoked to inform the page that it is being detached from the current request.
void	discardPersistentFieldChanges() Discards all persistent field changes for the page containing the component.
int	getAttachCount() Returns the number of times the page has been attached to a request.
ComponentPageElement	getComponentElementByNestedId(String nestedId) Retrieves a component element by its nested id (a sequence of simple ids, separated by dots).
Object	getFieldChange(String nestedId, String fieldName) Gets a change for a field within the component.
org.slf4j.Logger	getLogger() Returns the logger of the root component element.
String	getName() Returns the short, logical name for the page.
Component	getRootComponent() The root component of the page.
ComponentPageElement	getRootElement() The root component of the page.
ComponentResourceSelector	getSelector() The selector (which includes Locale) used when the page was constructor.
Page.Stats	getStats() Returns the page construction statistics for this page.
boolean	hasResetListeners() Returns true if there are any PageResetListener listeners.
void	loaded() Inform the page that it is now completely loaded.
void	pageReset() Invoked to notify PageResetListener listeners.
void	persistFieldChange(ComponentResources resources, String fieldName, Object newValue) Posts a change to a persistent field.
void	removeLifecycleListener(PageLifecycleListener listener) Deprecated. in 5.3.4, due to introduction of PageLifecycleCallbackHub.addPageLoadedCallback(Runnable)
void	setRootElement(ComponentPageElement component) Invoked during page construction time to connect the page's root component to the page instance.
void	setStats(Page.Stats stats) Invoked once at the end of page construction, to provide page construction statistics.

Methods inherited from interface org.apache.tapestry5.runtime.PageLifecycleCallbackHub

addPageAttachedCallback, addPageDetachedCallback, addPageLoadedCallback, addResetCallback, addVerifyCallback

Method Detail

getName

String getName()

Returns the short, logical name for the page. This is the page name as it might included in an action or page render URL (though it will be converted to lower case when it is included).

getSelector

ComponentResourceSelector getSelector()

The selector (which includes Locale) used when the page was constructor.

setRootElement

void setRootElement(ComponentPageElement component)

Invoked during page construction time to connect the page's root component to the page instance.

getRootElement

ComponentPageElement getRootElement()

The root component of the page. This is the wrapper around the end developer's view of the page.

getRootComponent

Component getRootComponent()

The root component of the page. A convenience over invoking getRootElement().getComponent().

detached

boolean detached()

Invoked to inform the page that it is being detached from the current request. This occurs just before the page is returned to the page pool.

A page may be clean or dirty. A page is dirty if its dirty count is greater than zero (meaning that, during the render of the page, some components did not fully render), or if any of its listeners throw an exception from containingPageDidDetach().

The page pool should discard pages that are dirty, rather than store them into the pool.

Under Tapestry 5.2 and pool-less pages, the result is ignored; all mutable state is expected to be discarded automatically from the PerthreadManager. A future release of Tapestry will likely convert this method to type void.

Returns:

true if the page is "dirty", false otherwise

See Also:

PageLifecycleListener.containingPageDidDetach()

attached

void attached()

Invoked to inform the page that it is attached to the current request. This occurs when a page is first referenced within a request. If the page was created from scratch for this request, the call to loaded() will preceded the call to attached().

First all listeners have PageLifecycleListener.restoreStateBeforePageAttach() invoked, followed by PageLifecycleListener.containingPageDidAttach().

loaded

void loaded()

Inform the page that it is now completely loaded.

See Also:

PageLifecycleListener.containingPageDidLoad()

addLifecycleListener

void addLifecycleListener(PageLifecycleListener listener)

Deprecated. in 5.3.4; use PageLifecycleCallbackHub.addPageLoadedCallback(Runnable), PageLifecycleCallbackHub.addPageAttachedCallback(Runnable), or PageLifecycleCallbackHub.addPageDetachedCallback(Runnable) instead

Adds a listener that is notified of large scale page events.

removeLifecycleListener

void removeLifecycleListener(PageLifecycleListener listener)

Deprecated. in 5.3.4, due to introduction of PageLifecycleCallbackHub.addPageLoadedCallback(Runnable)

Removes a listener that was previously added.

Since:

5.2.0

getLogger

org.slf4j.Logger getLogger()

Returns the logger of the root component element. Any logging about page construction or activity should be sent to this logger.

getComponentElementByNestedId

ComponentPageElement getComponentElementByNestedId(String nestedId)

Retrieves a component element by its nested id (a sequence of simple ids, separated by dots). The individual names in the nested id are matched without regards to case. A nested id of '' (the empty string) returns the root element of the page.

Throws:

IllegalArgumentException - if the nestedId does not correspond to a component

persistFieldChange

void persistFieldChange(ComponentResources resources,
                        String fieldName,
                        Object newValue)

Posts a change to a persistent field.

Parameters:

resources - the component resources for the component or mixin containing the field whose value changed

fieldName - the name of the field

newValue - the new value for the field

getFieldChange

Object getFieldChange(String nestedId,
                      String fieldName)

Gets a change for a field within the component.

Parameters:

nestedId - the nested component id of the component containing the field

fieldName - the name of the persistent field

Returns:

the value, or null if no value is stored

discardPersistentFieldChanges

void discardPersistentFieldChanges()

Discards all persistent field changes for the page containing the component. Changes are eliminated from persistent storage (such as the Session) which will take effect in the next request (the attached page instance is not affected).

addResetListener

void addResetListener(PageResetListener listener)

Deprecated. in 5.3.4,

Adds a new listener for page reset events.

Parameters:

listener - will receive notifications when the page is accessed from a different page

Since:

5.2.0

hasResetListeners

boolean hasResetListeners()

Returns true if there are any PageResetListener listeners.

Since:

5.2.0

pageReset

void pageReset()

Invoked to notify PageResetListener listeners.

setStats

void setStats(Page.Stats stats)

Invoked once at the end of page construction, to provide page construction statistics.

Since:

5.3

getStats

Page.Stats getStats()

Returns the page construction statistics for this page.

getAttachCount

int getAttachCount()

Returns the number of times the page has been attached to a request. This is a rough measure of how important the page is, relative to other pages. This value is volatile, changing constantly.

Since:

5.3