001/*
002 * Copyright 2002-2015 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.messaging.converter;
018
019import org.springframework.messaging.Message;
020import org.springframework.messaging.MessageHeaders;
021
022/**
023 * An extended {@link MessageConverter} SPI with conversion hint support.
024 *
025 * <p>In case of a conversion hint being provided, the framework will call
026 * these extended methods if a converter implements this interface, instead
027 * of calling the regular {@code fromMessage} / {@code toMessage} variants.
028 *
029 * @author Juergen Hoeller
030 * @since 4.2.1
031 */
032public interface SmartMessageConverter extends MessageConverter {
033
034        /**
035         * A variant of {@link #fromMessage(Message, Class)} which takes an extra
036         * conversion context as an argument, allowing to take e.g. annotations
037         * on a payload parameter into account.
038         * @param message the input message
039         * @param targetClass the target class for the conversion
040         * @param conversionHint an extra object passed to the {@link MessageConverter},
041         * e.g. the associated {@code MethodParameter} (may be {@code null}}
042         * @return the result of the conversion, or {@code null} if the converter cannot
043         * perform the conversion
044         * @see #fromMessage(Message, Class)
045         */
046        Object fromMessage(Message<?> message, Class<?> targetClass, Object conversionHint);
047
048        /**
049         * A variant of {@link #toMessage(Object, MessageHeaders)} which takes an extra
050         * conversion context as an argument, allowing to take e.g. annotations
051         * on a return type into account.
052         * @param payload the Object to convert
053         * @param headers optional headers for the message (may be {@code null})
054         * @param conversionHint an extra object passed to the {@link MessageConverter},
055         * e.g. the associated {@code MethodParameter} (may be {@code null}}
056         * @return the new message, or {@code null} if the converter does not support the
057         * Object type or the target media type
058         * @see #toMessage(Object, MessageHeaders)
059         */
060        Message<?> toMessage(Object payload, MessageHeaders headers, Object conversionHint);
061
062}