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

Nested Classes
Modifier and Type Interface Description

static class Page.Stats
Page construction statistics for the page.

Method Summary

All Methods Instance Methods Abstract Methods Deprecated Methods
Modifier and Type	Method	Description
`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.
`boolean`	`isExactParameterCountMatch()`	Returns true if extract parameter count matching is enabled.
`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:
    
    UnknownValueException - 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
  - isExactParameterCountMatch
```
@NonVisual
boolean isExactParameterCountMatch()
```
    Returns true if extract parameter count matching is enabled.
    
    Since:
    
    5.4
    
    See Also:
    
    MetaDataConstants.UNKNOWN_ACTIVATION_CONTEXT_CHECK

Interface Page

Nested Class Summary

Method Summary

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

Method Detail

getName

getSelector

setRootElement

getRootElement

getRootComponent

detached

attached

loaded

addLifecycleListener

removeLifecycleListener

getLogger

getComponentElementByNestedId

persistFieldChange

getFieldChange

discardPersistentFieldChanges

addResetListener

hasResetListeners

pageReset

setStats

getStats

getAttachCount

isExactParameterCountMatch