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package javax.faces.application;
import javax.faces.context.FacesContext;
/**
* <p>
* <span class="changed_modified_2_0 changed_modified_2_2">A</span>
* <strong>NavigationHandler</strong> is passed the outcome string returned by an application action
* invoked for this application, and will use this (along with related state information) to choose
* the view to be displayed next.
* </p>
*
* <p>
* A default implementation of <code>NavigationHandler</code> must be provided by the JSF
* implementation, which will be utilized unless <code>setNavigationHandler()</code> is called to
* establish a different one. <span class="changed_added_2_0">An implementation of this class must
* be thread-safe.</span> This default instance will compare the view identifier of the current
* view, the specified action binding, and the specified outcome against any navigation rules
* provided in <code>faces-config.xml</code> file(s). If a navigation case matches, the current view
* will be changed by a call to <code>FacesContext.setViewRoot()</code>. Note that a
* <code>null</code> outcome value will never match any navigation rule, so it can be used as an
* indicator that the current view should be redisplayed.
* </p>
*/
public abstract class NavigationHandler {
/**
* <p>
* <span class="changed_modified_2_0">Perform</span> navigation processing based on the state
* information in the specified {@link FacesContext}, plus the outcome string returned by an
* executed application action.
* </p>
*
* <p class="changed_added_2_0">
* If the implementation class also extends {@link ConfigurableNavigationHandler}, the
* implementation must guarantee that the logic used in a call to
* {@link ConfigurableNavigationHandler#getNavigationCase} is used in this method to determine
* the correct navigation.
* </p>
*
* <p class="changed_added_2_0">
* This method must set the render targets (used in partial rendering) to
* <code>render all </code> invoking
* {@link javax.faces.context.PartialViewContext#setRenderAll}) if the view identifier has
* changed as the result of an application action (to take into account
* <code>Ajax requests</code>).
* </p>
*
* @param context The {@link FacesContext} for the current request
* @param fromAction The action binding expression that was evaluated to retrieve the specified
* outcome, or <code>null</code> if the outcome was acquired by some other means
* @param outcome The logical outcome returned by a previous invoked application action (which
* may be <code>null</code>)
*
* @throws NullPointerException if <code>context</code> is <code>null</code>
*/
public abstract void handleNavigation(FacesContext context, String fromAction, String outcome);
/**
* <p class="changed_added_2_2">
* Overloaded variant of
* {@link #handleNavigation(javax.faces.context.FacesContext, java.lang.String, java.lang.String)}
* that allows the caller to provide the defining document id for a flow to be entered by this
* navigation. For backward compatibility with decorated {@code NavigationHandler}
* implementations that conform to an earlier version of the specification, an implementation is
* provided that calls through to
* {@link #handleNavigation(javax.faces.context.FacesContext, java.lang.String, java.lang.String)},
* ignoring the {@code toFlowDocumentId} parameter.
* </p>
*
* @param context The {@link FacesContext} for the current request
* @param fromAction The action binding expression that was evaluated to retrieve the specified
* outcome, or <code>null</code> if the outcome was acquired by some other means
* @param outcome The logical outcome returned by a previous invoked application action (which
* may be <code>null</code>)
* @param toFlowDocumentId The defining document id of the flow into which this navigation will
* cause entry.
*
* @throws NullPointerException if <code>context</code> is <code>null</code>
*/
public void handleNavigation(FacesContext context, String fromAction, String outcome, String toFlowDocumentId) {
this.handleNavigation(context, fromAction, outcome);
}
}