SPR-8997 Add HttpServletResponse to FlashMapManager contract.

This change makes the HttpServletResponse available to the methods
of FlashMapManager in addition to the HttpServletRequest.

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/DispatcherServlet.java

@@ -815,7 +815,7 @@ public class DispatcherServlet extends FrameworkServlet {
 			}
 		}
 
-		this.flashMapManager.requestStarted(request);
+		this.flashMapManager.requestStarted(request, response);
 
 		// Make framework objects available to handlers and view objects.
 		request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, getWebApplicationContext());
@@ -827,7 +827,7 @@ public class DispatcherServlet extends FrameworkServlet {
 			doDispatch(request, response);
 		}
 		finally {
-			this.flashMapManager.requestCompleted(request);
+			this.flashMapManager.requestCompleted(request, response);
 			
 			// Restore the original attribute snapshot, in case of an include.
 			if (attributesSnapshot != null) {

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/FlashMap.java

@@ -63,6 +63,8 @@ public final class FlashMap extends HashMap<String, Object> implements Comparabl
 	/**
 	 * Create a new instance with an id uniquely identifying the creator of 
 	 * this FlashMap.
+	 * @param createdBy identifies the FlashMapManager instance that created
+	 * 	and will manage this FlashMap instance (e.g. via a hashCode)  
 	 */
 	public FlashMap(int createdBy) {
 		this.createdBy = createdBy;

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/FlashMapManager.java

@@ -17,6 +17,7 @@
 package org.springframework.web.servlet;
 
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
 /**
  * A strategy interface for storing, retrieving, and managing {@code FlashMap}
@@ -64,8 +65,9 @@ public interface FlashMapManager {
 	 * 	<li>Clean expired FlashMap instances.
 	 * </ol>
 	 * @param request the current request
+	 * @param response the current response
 	 */
-	void requestStarted(HttpServletRequest request);
+	void requestStarted(HttpServletRequest request, HttpServletResponse response);
 
 	/**
 	 * Start the expiration period of the "output" FlashMap save it in the
@@ -73,7 +75,8 @@ public interface FlashMapManager {
 	 * <p>The "output" FlashMap should not be saved if it is empty or if it was
 	 * not created by the current FlashMapManager instance.
 	 * @param request the current request
+	 * @param response the current response
 	 */
-	void requestCompleted(HttpServletRequest request);
+	void requestCompleted(HttpServletRequest request, HttpServletResponse response);
 
 }

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/support/DefaultFlashMapManager.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpSession;
 
 import org.apache.commons.logging.Log;
@@ -64,7 +65,7 @@ public class DefaultFlashMapManager implements FlashMapManager {
 	 * {@inheritDoc}
 	 * <p>An HTTP session is never created by this method.
 	 */
-	public void requestStarted(HttpServletRequest request) {
+	public final void requestStarted(HttpServletRequest request, HttpServletResponse response) {
 		if (request.getAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE) != null) {
 			return;
 		}
@@ -164,9 +165,9 @@ public class DefaultFlashMapManager implements FlashMapManager {
 	}
 	
 	/**
-	 * Iterate all flash maps and remove expired ones.
+	 * Check and remove expired FlashMaps instances.
 	 */
-	private void removeExpiredFlashMaps(HttpServletRequest request) {
+	protected void removeExpiredFlashMaps(HttpServletRequest request) {
 		List<FlashMap> allMaps = retrieveFlashMaps(request, false);
 		if (CollectionUtils.isEmpty(allMaps)) {
 			return;
@@ -189,7 +190,7 @@ public class DefaultFlashMapManager implements FlashMapManager {
 	 * {@inheritDoc}
 	 * <p>An HTTP session is never created if the "output" FlashMap is empty.
 	 */
-	public void requestCompleted(HttpServletRequest request) {
+	public void requestCompleted(HttpServletRequest request, HttpServletResponse response) {
 		FlashMap flashMap = (FlashMap) request.getAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE);
 		if (flashMap == null) {
 			throw new IllegalStateException("requestCompleted called but \"output\" FlashMap was never created");
@@ -198,24 +199,35 @@ public class DefaultFlashMapManager implements FlashMapManager {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Saving FlashMap=" + flashMap);
 			}
-			onSaveFlashMap(flashMap, request);
-			retrieveFlashMaps(request, true).add(flashMap);
+			onSaveFlashMap(flashMap, request, response);
+			saveFlashMap(flashMap, request, response);
 		}
 	}
 	
 	/**
-	 * Update a FlashMap before it is stored in the HTTP Session.
+	 * Update a FlashMap before it is stored in the underlying storage.
 	 * <p>The default implementation starts the expiration period and ensures the
 	 * target request path is decoded and normalized if it is relative. 
 	 * @param flashMap the flash map to be saved
 	 * @param request the current request
+	 * @param response the current response
 	 */
-	protected void onSaveFlashMap(FlashMap flashMap, HttpServletRequest request) {
+	protected void onSaveFlashMap(FlashMap flashMap, HttpServletRequest request, HttpServletResponse response) {
 		String targetPath = flashMap.getTargetRequestPath();
 		flashMap.setTargetRequestPath(decodeAndNormalizePath(targetPath, request));
 		flashMap.startExpirationPeriod(this.flashTimeout);
 	}
 
+	/**
+	 * Save the FlashMap in the underlying storage.
+	 * @param flashMap the FlashMap to save
+	 * @param request the current request
+	 * @param response the current response
+	 */
+	protected void saveFlashMap(FlashMap flashMap, HttpServletRequest request, HttpServletResponse response) {
+		retrieveFlashMaps(request, true).add(flashMap);
+	}
+	
 	private String decodeAndNormalizePath(String path, HttpServletRequest request) {
 		if (path != null) {
 			path = this.urlPathHelper.decodeRequestString(request, path);