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.handler.invocation;
018
019import org.springframework.core.MethodParameter;
020import org.springframework.lang.Nullable;
021import org.springframework.messaging.Message;
022
023/**
024 * Strategy interface to handle the value returned from the invocation of a
025 * method handling a {@link Message}.
026 *
027 * @author Rossen Stoyanchev
028 * @since 4.0
029 */
030public interface HandlerMethodReturnValueHandler {
031
032        /**
033         * Whether the given {@linkplain MethodParameter method return type} is
034         * supported by this handler.
035         * @param returnType the method return type to check
036         * @return {@code true} if this handler supports the supplied return type;
037         * {@code false} otherwise
038         */
039        boolean supportsReturnType(MethodParameter returnType);
040
041        /**
042         * Handle the given return value.
043         * @param returnValue the value returned from the handler method
044         * @param returnType the type of the return value. This type must have previously
045         * been passed to {@link #supportsReturnType(org.springframework.core.MethodParameter)}
046         * and it must have returned {@code true}.
047         * @param message the message that caused this method to be called
048         * @throws Exception if the return value handling results in an error
049         */
050        void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType, Message<?> message)
051                        throws Exception;
052
053}