public class ELFlash extends Flash
How this implementation works
This class is an application singleton. It has one ivar, innerMap. Entries are added to and removed from this map as needed according to how the flash scope is defined in the spec. This implementation never touches the session, nor does it cause the session to be created.
Most of the hairy logic is encapsulated with in the inner class PreviousNextFlashInfoManager. An instance of this class is obtained by calling one of the variants of getCurrentFlashManager(). When the instance is no longer needed for this request, call releaseCurrentFlashManager().
Two very important methods are getPhaseMapForWriting() and getPhaseMapForReading(). These methods are the basis for the Map implementation methods. Methods that need to write to the map use getPhaseMapForWriting(), those that need to read use getPhaseMapForReading(). These methods allow for the laziness that allows us to only incur a cost when the flash is actually written to.
The operation of this class is intimately tied to the request processing lifecycle. Let's break down every run thru the request processing lifecycle into two parts called "previous" and "next". We use the names "previous" and "next" to indicate the persistence and timing of the data that is stored in the flash. Consider two runs through the requset processing lifecle: N and N+1. On request N, there is no "previous" request. On Request N, any writes to the flash that happen during RENDER RESPONSE go to the "next" flash map. This means they are available for the ENTIRE run though the request processing lifecycle on request N+1. Any entries put into the "next" flash map on request N will be expired at the end of request N+1. Now, when we get into request N+1 what was considered "next" on request N, is now called "previous" from the perspective of request N+1. Any reads from the flash during request N+1 come from the "previous" map. Any writes to the flash before RENDER RESPONSE go to the "previous" map. Any writes to the flash during RENDER RESPNOSE go to the "next" map.
Modifier and Type | Field and Description |
---|---|
static String |
ACT_AS_DO_LAST_PHASE_ACTIONS |
NULL_VALUE
Modifier and Type | Method and Description |
---|---|
void |
clear() |
protected Object |
clone() |
boolean |
containsKey(Object key) |
boolean |
containsValue(Object value) |
void |
doLastPhaseActions(FacesContext context,
boolean outgoingResponseIsRedirect)
This is the most magic of methods.
|
void |
doPostPhaseActions(FacesContext context)
Called after the execution of every lifecycle phase, this method allows implementations to take the necessary actions to provide the Flash scope contract as it applies to the request procesing lifecycle. |
void |
doPrePhaseActions(FacesContext context)
Called before the execution of every lifecycle phase, this method allows implementations to take the necessary actions to provide the Flash scope contract as it applies to the request procesing lifecycle. |
Set<Map.Entry<String,Object>> |
entrySet() |
Object |
get(Object key) |
static Map<String,Object> |
getFlash()
Returns the flash
Map for this application. |
boolean |
isEmpty() |
boolean |
isKeepMessages()
Return the value of this JavaBeans property for the flash for this session. |
boolean |
isRedirect()
Return the value of this property for the flash for this session. |
void |
keep(String key)
Causes a value stored with a
previous call to |
Set<String> |
keySet() |
Object |
put(String key,
Object value) |
void |
putAll(Map<? extends String,?> t) |
void |
putNow(String key,
Object value)
Puts a value in the flash so that it can be accessed on this traversal of the lifecycle, rather than on the next traversal. |
Object |
remove(Object key) |
void |
setKeepMessages(boolean newValue)
Setter for |
void |
setRedirect(boolean newValue)
Setting this property to
|
int |
size() |
String |
toString() |
Collection<Object> |
values() |
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll
public static final String ACT_AS_DO_LAST_PHASE_ACTIONS
public static Map<String,Object> getFlash()
Returns the flash Map
for this application. This is
a convenience method that calls
FacesContext.getCurrentInstance()
and then calls the
overloaded getFlash()
that takes a
FacesContext
with it.
Map
for this session.public boolean isKeepMessages()
Flash
Return the value of this JavaBeans
property for the flash for this session. This value determines
whether or not any FacesMessage
instances queued in the current FacesContext
must be preserved so they are
accessible on the next traversal of the lifecycle on this
session, regardless of the request being a redirect after post,
or a normal postback. Map
accesses for the special
key “keepMessages
” must return the value
of this JavaBeans property.
Jakarta Expression Language Usage Example
First page
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:c="http://xmlns.jcp.org/jsp/jstl/core"> <!-- extra code removed --> <c:set target="#{flash}" property="keepMessages" value="true" />
Next page
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://xmlns.jcp.org/jsf/html"> <!-- extra code removed --> <h:messages /> Any messages present on the first page must be displayed on this page.
isKeepMessages
in class Flash
public void setKeepMessages(boolean newValue)
Flash
Setter for keepMessages
JavaBeans property. See Flash.isKeepMessages()
.
setKeepMessages
in class Flash
newValue
- the new value for this property on this session.public boolean isRedirect()
Flash
Return the value of this property
for the flash for this session. This must be false
unless:
Flash.setRedirect(boolean)
was called for the current
lifecycle traversal with true
as the
argument.
The current lifecycle traversal for this session is in the
“execute” phase and the previous traversal had Flash.setRedirect(boolean)
called with true
as the
argument.
isRedirect
in class Flash
public void setRedirect(boolean newValue)
Flash
Setting this property to
true
indicates that the next request on this session
will be a redirect. Recall that on a redirect, the server sends
a special response to the client instructing it to issue a new
request to a specific URI. The implementation must insure that
reading the value of this property on that request will return
true
.
Jakarta Expression Language Usage Example
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:c="http://xmlns.jcp.org/jsp/jstl/core"> <!-- extra code removed --> <c:set target="#{flash}" property="redirect" value="true" />
setRedirect
in class Flash
newValue
- the new value for this property on this session.public boolean containsKey(Object key)
public boolean containsValue(Object value)
public Collection<Object> values()
public int size()
public void clear()
protected Object clone() throws CloneNotSupportedException
clone
in class Object
CloneNotSupportedException
public boolean isEmpty()
public void keep(String key)
Flash
Causes a value stored with a
previous call to Flash.putNow(java.lang.String, java.lang.Object)
, its Jakarta Expression Language equivalent, or to the
request Map
, to be promoted to the flash so that is
available on the next traversal through the lifecycle on this
session.
keep
in class Flash
key
- if argument key
is the name of an entry
previously stored to the flash on this traversal through the
lifecycle via a call to Flash.putNow(java.lang.String, java.lang.Object)
, or to a set to the EL
expression #{flash.now.<key>}
, or to the
request Map
, to be promoted to the flash as if a call
to put()
or a set to the expression
#{flash.<key>}
was being called.public void putNow(String key, Object value)
Flash
Puts a value in the flash so that it can be accessed on this traversal of the lifecycle, rather than on the next traversal. This is simply an alias for putting a value in the request map.
Jakarta Expression Language Usage Example
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:c="http://xmlns.jcp.org/jsp/jstl/core"> <!-- extra code removed --> <c:set target="#{flash.now}" property="bar" value="barValue" /> <p>Value of \#{flash.now.bar}, should be barValue.</p> <h:outputText value="#{flash.now.bar}" />
public void doPrePhaseActions(FacesContext context)
Flash
Called before the execution of every lifecycle phase, this method allows implementations to take the necessary actions to provide the Flash scope contract as it applies to the request procesing lifecycle.
doPrePhaseActions
in class Flash
context
- the FacesContext
for this request.public void doPostPhaseActions(FacesContext context)
Flash
Called after the execution of every lifecycle phase, this method allows implementations to take the necessary actions to provide the Flash scope contract as it applies to the request procesing lifecycle.
doPostPhaseActions
in class Flash
context
- the FacesContext
for this request.public void doLastPhaseActions(FacesContext context, boolean outgoingResponseIsRedirect)
This is the most magic of methods. There are several scenarios
in which this method can be called, but the first time it is
called for a request it takes action, while on subsequent times
it returns without taking action. This is due to the call to
releaseCurrentFlashManager(java.util.Map<java.lang.Object, java.lang.Object>)
. After this call, any calls
to getCurrentFlashManager(java.util.Map<java.lang.Object, java.lang.Object>, boolean)
will return null.
Scenario 1: normal request ending. This will be called after the RENDER_RESPONSE phase executes. outgoingResponseIsRedirect will be false.
Scenario 2: navigationHandler asks extContext for redirect. In this case, extContext calls this method directly, outgoingResponseIsRedirect will be true.
Scenario 3: extContext.flushBuffer(): As far as I can tell, this is only called in the JSP case, but it's good to call it from there anyway, because we need to write our cookie before the response is committed. outgoingResponseIsRedirect is false.
Scenario 4: after rendering the response in JSP, but before the buffer is flushed. In the JSP case, I've found this necessary because the call to extContext.flushBuffer() is too late, the response has already been committed by that point. outgoingResponseIsRedirect is false.
Comments to: faces-dev@eclipse.org.
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