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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</a>
* <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);
}
}