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
022import org.springframework.lang.Nullable;
023
024/**
025 * A strategy interface for retrieving and saving FlashMap instances.
026 * See {@link FlashMap} for a general overview of flash attributes.
027 *
028 * @author Rossen Stoyanchev
029 * @since 3.1
030 * @see FlashMap
031 */
032public interface FlashMapManager {
033
034        /**
035         * Find a FlashMap saved by a previous request that matches to the current
036         * request, remove it from underlying storage, and also remove other
037         * expired FlashMap instances.
038         * <p>This method is invoked in the beginning of every request in contrast
039         * to {@link #saveOutputFlashMap}, which is invoked only when there are
040         * flash attributes to be saved - i.e. before a redirect.
041         * @param request the current request
042         * @param response the current response
043         * @return a FlashMap matching the current request or {@code null}
044         */
045        @Nullable
046        FlashMap retrieveAndUpdate(HttpServletRequest request, HttpServletResponse response);
047
048        /**
049         * Save the given FlashMap, in some underlying storage and set the start
050         * of its expiration period.
051         * <p><strong>NOTE:</strong> Invoke this method prior to a redirect in order
052         * to allow saving the FlashMap in the HTTP session or in a response
053         * cookie before the response is committed.
054         * @param flashMap the FlashMap to save
055         * @param request the current request
056         * @param response the current response
057         */
058        void saveOutputFlashMap(FlashMap flashMap, HttpServletRequest request, HttpServletResponse response);
059
060}