001/*
002 * Copyright 2002-2014 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.servlet;
018
019import javax.servlet.http.HttpServletRequest;
020import javax.servlet.http.HttpServletResponse;
021
022/**
023 * A strategy interface for retrieving and saving FlashMap instances.
024 * See {@link FlashMap} for a general overview of flash attributes.
025 *
026 * @author Rossen Stoyanchev
027 * @since 3.1
028 * @see FlashMap
029 */
030public interface FlashMapManager {
031
032        /**
033         * Find a FlashMap saved by a previous request that matches to the current
034         * request, remove it from underlying storage, and also remove other
035         * expired FlashMap instances.
036         * <p>This method is invoked in the beginning of every request in contrast
037         * to {@link #saveOutputFlashMap}, which is invoked only when there are
038         * flash attributes to be saved - i.e. before a redirect.
039         * @param request the current request
040         * @param response the current response
041         * @return a FlashMap matching the current request or {@code null}
042         */
043        FlashMap retrieveAndUpdate(HttpServletRequest request, HttpServletResponse response);
044
045        /**
046         * Save the given FlashMap, in some underlying storage and set the start
047         * of its expiration period.
048         * <p><strong>NOTE:</strong> Invoke this method prior to a redirect in order
049         * to allow saving the FlashMap in the HTTP session or in a response
050         * cookie before the response is committed.
051         * @param flashMap the FlashMap to save
052         * @param request the current request
053         * @param response the current response
054         */
055        void saveOutputFlashMap(FlashMap flashMap, HttpServletRequest request, HttpServletResponse response);
056
057}