Package com.sun.faces.context.flash

Class ELFlash

java.lang.Object
jakarta.faces.context.Flash
com.sun.faces.context.flash.ELFlash
All Implemented Interfaces:
Map<String,Object>
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.

  • Field Details

    • ACT_AS_DO_LAST_PHASE_ACTIONS

      public static final String ACT_AS_DO_LAST_PHASE_ACTIONS

  • Method Details

    • getFlash

      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.

      Returns:
      The flash Map for this session.

    • isKeepMessages

      public boolean isKeepMessages()
      Description copied from class: 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="jakarta.tags.core">
    <!-- extra code removed -->
      <c:set target="#{flash}" property="keepMessages" value="true" />

      Next page 

       
    <html xmlns="http://www.w3.org/1999/xhtml"
          xmlns:h="jakarta.faces.html">
    <!-- extra code removed -->
      <h:messages /> Any messages present on the first page must be displayed on
      this page.
      Specified by:
      isKeepMessages in class Flash
      Returns:
      the boolean flag whether keeping messages or not.

    • setKeepMessages

      public void setKeepMessages(boolean newValue)
      Description copied from class: Flash

      Setter for keepMessages JavaBeans property. See Flash.isKeepMessages().

      Specified by:
      setKeepMessages in class Flash
      Parameters:
      newValue - the new value for this property on this session.

    • isRedirect

      public boolean isRedirect()
      Description copied from class: 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.

      Specified by:
      isRedirect in class Flash
      Returns:
      the value of this property for the flash for this session.

    • setRedirect

      public void setRedirect(boolean newValue)
      Description copied from class: 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="jakarta.tags.core">
    <!-- extra code removed -->
      <c:set target="#{flash}" property="redirect" value="true" />
      Specified by:
      setRedirect in class Flash
      Parameters:
      newValue - the new value for this property on this session.

    • get

      public Object get(Object key)

    • put

      public Object put(String key, Object value)

    • remove

      public Object remove(Object key)

    • containsKey

      public boolean containsKey(Object key)

    • containsValue

      public boolean containsValue(Object value)

    • putAll

      public void putAll(Map<? extends String,?> t)

    • values

      public Collection<Object> values()

    • size

      public int size()

    • clear

      public void clear()

    • clone

      protected Object clone() throws CloneNotSupportedException
      Overrides:
      clone in class Object
      Throws:
      CloneNotSupportedException

    • entrySet

      public Set<Map.Entry<String,Object>> entrySet()

    • isEmpty

      public boolean isEmpty()

    • keySet

      public Set<String> keySet()

    • keep

      public void keep(String key)
      Description copied from class: 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.

      Specified by:
      keep in class Flash
      Parameters:
      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.

    • putNow

      public void putNow(String key, Object value)
      Description copied from class: 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="jakarta.tags.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}" />
      Specified by:
      putNow in class Flash
      Parameters:
      key - the key for this entry
      value - the value for this entry

    • doPrePhaseActions

      public void doPrePhaseActions(FacesContext context)
      Description copied from class: 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.

      Specified by:
      doPrePhaseActions in class Flash
      Parameters:
      context - the FacesContext for this request.

    • doPostPhaseActions

      public void doPostPhaseActions(FacesContext context)
      Description copied from class: 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.

      Specified by:
      doPostPhaseActions in class Flash
      Parameters:
      context - the FacesContext for this request.

    • doLastPhaseActions

      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 was 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.

      Parameters:
      context - the involved faces context
      outgoingResponseIsRedirect - whether outgoing response is redirect

    • toString

      public String toString()
      Overrides:
      toString in class Object