Fixed bug in handling of null view.

spring-webflow/src/main/java/org/springframework/webflow/executor/mvc/PortletFlowController.java

@@ -45,25 +45,26 @@ import org.springframework.webflow.executor.support.ResponseInstructionHandler;
  * Point of integration between Spring Portlet MVC and Spring Web Flow: a {@link Controller} that routes incoming
  * portlet requests to one or more managed flow executions.
  * <p>
- * Requests into the web flow system are handled by a {@link FlowExecutor}, which this class delegates to. Consult the
- * JavaDoc of that class for more information on how requests are processed.
+ * Requests into the web flow system are handled by a {@link FlowExecutor}, which this class delegates to. Consult
+ * the JavaDoc of that class for more information on how requests are processed.
  * <p>
  * Note: a single <code>PortletFlowController</code> may execute all flows within your application. See the
- * <code>phonebook-portlet</code> sample application for examples of the various strategies for launching and resuming
- * flow executions in a Portlet environment.
+ * <code>phonebook-portlet</code> sample application for examples of the various strategies for launching and
+ * resuming flow executions in a Portlet environment.
  * <p>
- * It is also possible to customize the {@link FlowExecutorArgumentHandler} strategy to allow for different types of
- * controller parameterization, for example perhaps in conjunction with a REST-style request mapper.
+ * It is also possible to customize the {@link FlowExecutorArgumentHandler} strategy to allow for different types
+ * of controller parameterization, for example perhaps in conjunction with a REST-style request mapper.
  * <p>
  * Integrating Spring Web Flow into a Portlet environment puts some minor contraints on your flows. These constraints
  * result from technical limitations in the Portlet API, for instance the fact that a render request cannot issue a
  * redirect. Keep the following in mind when developing Portlets using Spring Web Flow:
  * <ul>
  * <li>Using the well known POST-REDIRECT-GET idiom, for instance using <i>alwaysRedirectOnPause</i> or the
- * "redirect:" view prefix, does not make sense in a Portlet environment where the Portlet container handles this using
- * a seperate <i>render phase</i>. In other words, a {@link FlowExecutionRedirect} is not supportd.</li>
+ * "redirect:" view prefix, does not make sense in a Portlet environment where the Portlet container handles this
+ * using a seperate <i>render phase</i>. In other words, a {@link FlowExecutionRedirect} is not supportd.</li>
  * <li>This controller will launch a new flow execution <i>every time</i> it handles a render request without having
- * previously handled an action request (for the same session) or the render request containing a flow execution key.</li>
+ * previously handled an action request (for the same session) or the render request containing a flow execution key.
+ * </li>
  * <li>Launching new flow executions is done in the render phase. As a result the first view selection your flow makes
  * cannot be a {@link FlowDefinitionRedirect} or an {@link ExternalRedirect}.</li>
  * </ul>
@@ -193,16 +194,21 @@ public class PortletFlowController extends AbstractController implements Initial
 		final PortletExternalContext context = new PortletExternalContext(getPortletContext(), request, response);
 		final String flowExecutionKey = argumentHandler.extractFlowExecutionKey(context);
 		final String eventId = argumentHandler.extractEventId(context);
+
 		// signal the event against the flow execution, returning the next response instruction
 		final ResponseInstruction responseInstruction = flowExecutor.resume(flowExecutionKey, eventId, context);
+
 		new ResponseInstructionHandler() {
 			protected void handleApplicationView(ApplicationView view) throws Exception {
 				// response instruction is a forward to an "application view"
 				if (responseInstruction.isActiveView()) {
 					// is an "active" forward returned by a view-state (not an end-state) --
 					// set the flow execution key render parameter to support browser refresh
-					response.setRenderParameter(argumentHandler.getFlowExecutionKeyArgumentName(), responseInstruction
-							.getFlowExecutionKey());
+					// we need to do this because the responseInstruction stored in the session
+					// below will be removed from the session when the next render request
+					// extracts it (see extractActionResponseInstruction)
+					response.setRenderParameter(argumentHandler.getFlowExecutionKeyArgumentName(),
+							responseInstruction.getFlowExecutionKey());
 				}
 				// make response instruction available for rendering during the render phase of this portlet request
 				exposeToRenderPhase(responseInstruction, request);
@@ -217,8 +223,8 @@ public class PortletFlowController extends AbstractController implements Initial
 
 			protected void handleFlowExecutionRedirect(FlowExecutionRedirect redirect) throws Exception {
 				// is a flow execution redirect: simply expose key parameter to support refresh during render phase
-				response.setRenderParameter(argumentHandler.getFlowExecutionKeyArgumentName(), responseInstruction
-						.getFlowExecutionKey());
+				response.setRenderParameter(argumentHandler.getFlowExecutionKeyArgumentName(),
+						responseInstruction.getFlowExecutionKey());
 			}
 
 			protected void handleExternalRedirect(ExternalRedirect redirect) throws Exception {
@@ -228,6 +234,12 @@ public class PortletFlowController extends AbstractController implements Initial
 			}
 
 			protected void handleNull() throws Exception {
+				if (responseInstruction.getFlowExecutionContext().isActive()) {
+					// flow execution is still active
+					// set the flow execution key render parameter to support browser refresh
+					response.setRenderParameter(argumentHandler.getFlowExecutionKeyArgumentName(),
+							responseInstruction.getFlowExecutionKey());
+				}
 				// make response instruction available for rendering during the render phase of this portlet request
 				exposeToRenderPhase(responseInstruction, request);
 			}
@@ -274,8 +286,8 @@ public class PortletFlowController extends AbstractController implements Initial
 			// forward to a view as part of an active conversation
 			ApplicationView forward = (ApplicationView) responseInstruction.getViewSelection();
 			Map model = new HashMap(forward.getModel());
-			argumentHandler.exposeFlowExecutionContext(responseInstruction.getFlowExecutionKey(), responseInstruction
-					.getFlowExecutionContext(), model);
+			argumentHandler.exposeFlowExecutionContext(
+					responseInstruction.getFlowExecutionKey(), responseInstruction.getFlowExecutionContext(), model);
 			return new ModelAndView(forward.getViewName(), model);
 		}
 		else if (responseInstruction.isNull()) {