001/* 002 * Copyright 2002-2017 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.lang.Nullable; 020import org.springframework.messaging.Message; 021import org.springframework.messaging.MessageHeaders; 022 023/** 024 * An extended {@link MessageConverter} SPI with conversion hint support. 025 * 026 * <p>In case of a conversion hint being provided, the framework will call 027 * these extended methods if a converter implements this interface, instead 028 * of calling the regular {@code fromMessage} / {@code toMessage} variants. 029 * 030 * @author Juergen Hoeller 031 * @since 4.2.1 032 */ 033public interface SmartMessageConverter extends MessageConverter { 034 035 /** 036 * A variant of {@link #fromMessage(Message, Class)} which takes an extra 037 * conversion context as an argument, allowing to take e.g. annotations 038 * on a payload parameter into account. 039 * @param message the input message 040 * @param targetClass the target class for the conversion 041 * @param conversionHint an extra object passed to the {@link MessageConverter}, 042 * e.g. the associated {@code MethodParameter} (may be {@code null}} 043 * @return the result of the conversion, or {@code null} if the converter cannot 044 * perform the conversion 045 * @see #fromMessage(Message, Class) 046 */ 047 @Nullable 048 Object fromMessage(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint); 049 050 /** 051 * A variant of {@link #toMessage(Object, MessageHeaders)} which takes an extra 052 * conversion context as an argument, allowing to take e.g. annotations 053 * on a return type into account. 054 * @param payload the Object to convert 055 * @param headers optional headers for the message (may be {@code null}) 056 * @param conversionHint an extra object passed to the {@link MessageConverter}, 057 * e.g. the associated {@code MethodParameter} (may be {@code null}} 058 * @return the new message, or {@code null} if the converter does not support the 059 * Object type or the target media type 060 * @see #toMessage(Object, MessageHeaders) 061 */ 062 @Nullable 063 Message<?> toMessage(Object payload, @Nullable MessageHeaders headers, @Nullable Object conversionHint); 064 065}