001/*
002 * Copyright 2002-2018 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.support;
018
019import java.util.Map;
020
021import javax.servlet.http.HttpServletRequest;
022
023import org.springframework.lang.Nullable;
024
025/**
026 * A contract for inspecting and potentially modifying request data values such
027 * as URL query parameters or form field values before they are rendered by a
028 * view or before a redirect.
029 *
030 * <p>Implementations may use this contract for example as part of a solution
031 * to provide data integrity, confidentiality, protection against cross-site
032 * request forgery (CSRF), and others or for other tasks such as automatically
033 * adding a hidden field to all forms and URLs.
034 *
035 * <p>View technologies that support this contract can obtain an instance to
036 * delegate to via {@link RequestContext#getRequestDataValueProcessor()}.
037 *
038 * @author Rossen Stoyanchev
039 * @since 3.1
040 */
041public interface RequestDataValueProcessor {
042
043        /**
044         * Invoked when a new form action is rendered.
045         * @param request the current request
046         * @param action the form action
047         * @param httpMethod the form HTTP method
048         * @return the action to use, possibly modified
049         */
050        String processAction(HttpServletRequest request, String action, String httpMethod);
051
052        /**
053         * Invoked when a form field value is rendered.
054         * @param request the current request
055         * @param name the form field name (if any)
056         * @param value the form field value
057         * @param type the form field type ("text", "hidden", etc.)
058         * @return the form field value to use, possibly modified
059         */
060        String processFormFieldValue(HttpServletRequest request, @Nullable String name, String value, String type);
061
062        /**
063         * Invoked after all form fields have been rendered.
064         * @param request the current request
065         * @return additional hidden form fields to be added, or {@code null} if none
066         */
067        @Nullable
068        Map<String, String> getExtraHiddenFields(HttpServletRequest request);
069
070        /**
071         * Invoked when a URL is about to be rendered or redirected to.
072         * @param request the current request
073         * @param url the URL value
074         * @return the URL to use, possibly modified
075         */
076        String processUrl(HttpServletRequest request, String url);
077
078}