001/* 002 * Copyright 2002-2012 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.mvc.support; 018 019import java.util.Collection; 020import java.util.Map; 021 022import org.springframework.ui.Model; 023import org.springframework.web.servlet.FlashMap; 024 025/** 026 * A specialization of the {@link Model} interface that controllers can use to 027 * select attributes for a redirect scenario. Since the intent of adding 028 * redirect attributes is very explicit -- i.e. to be used for a redirect URL, 029 * attribute values may be formatted as Strings and stored that way to make 030 * them eligible to be appended to the query string or expanded as URI 031 * variables in {@code org.springframework.web.servlet.view.RedirectView}. 032 * 033 * <p>This interface also provides a way to add flash attributes. For a 034 * general overview of flash attributes see {@link FlashMap}. You can use 035 * {@link RedirectAttributes} to store flash attributes and they will be 036 * automatically propagated to the "output" FlashMap of the current request. 037 * 038 * <p>Example usage in an {@code @Controller}: 039 * <pre class="code"> 040 * @RequestMapping(value = "/accounts", method = RequestMethod.POST) 041 * public String handle(Account account, BindingResult result, RedirectAttributes redirectAttrs) { 042 * if (result.hasErrors()) { 043 * return "accounts/new"; 044 * } 045 * // Save account ... 046 * redirectAttrs.addAttribute("id", account.getId()).addFlashAttribute("message", "Account created!"); 047 * return "redirect:/accounts/{id}"; 048 * } 049 * </pre> 050 * 051 * <p>A RedirectAttributes model is empty when the method is called and is never 052 * used unless the method returns a redirect view name or a RedirectView. 053 * 054 * <p>After the redirect, flash attributes are automatically added to the model 055 * of the controller that serves the target URL. 056 * 057 * @author Rossen Stoyanchev 058 * @since 3.1 059 */ 060public interface RedirectAttributes extends Model { 061 062 @Override 063 RedirectAttributes addAttribute(String attributeName, Object attributeValue); 064 065 @Override 066 RedirectAttributes addAttribute(Object attributeValue); 067 068 @Override 069 RedirectAttributes addAllAttributes(Collection<?> attributeValues); 070 071 @Override 072 RedirectAttributes mergeAttributes(Map<String, ?> attributes); 073 074 /** 075 * Add the given flash attribute. 076 * @param attributeName the attribute name; never {@code null} 077 * @param attributeValue the attribute value; may be {@code null} 078 */ 079 RedirectAttributes addFlashAttribute(String attributeName, Object attributeValue); 080 081 /** 082 * Add the given flash storage using a 083 * {@link org.springframework.core.Conventions#getVariableName generated name}. 084 * @param attributeValue the flash attribute value; never {@code null} 085 */ 086 RedirectAttributes addFlashAttribute(Object attributeValue); 087 088 /** 089 * Return the attributes candidate for flash storage or an empty Map. 090 */ 091 Map<String, ?> getFlashAttributes(); 092}