org.springframework.messaging.converter.MessageConverter Maven / Gradle / Ivy
/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.messaging.converter;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
/**
* A converter to turn the payload of a {@link Message} from serialized form to a typed
* Object and vice versa. The {@link MessageHeaders#CONTENT_TYPE} message header may be
* used to specify the media type of the message content.
*
* @author Mark Fisher
* @author Rossen Stoyanchev
* @since 4.0
*/
public interface MessageConverter {
/**
* Convert the payload of a {@link Message} from a serialized form to a typed Object
* of the specified target class. The {@link MessageHeaders#CONTENT_TYPE} header
* should indicate the MIME type to convert from.
* If the converter does not support the specified media type or cannot perform
* the conversion, it should return {@code null}.
* @param message the input message
* @param targetClass the target class for the conversion
* @return the result of the conversion, or {@code null} if the converter cannot
* perform the conversion
*/
@Nullable
Object fromMessage(Message message, Class targetClass);
/**
* Create a {@link Message} whose payload is the result of converting the given
* payload Object to serialized form. The optional {@link MessageHeaders} parameter
* may contain a {@link MessageHeaders#CONTENT_TYPE} header to specify the target
* media type for the conversion and it may contain additional headers to be added
* to the message.
*
If the converter does not support the specified media type or cannot perform
* the conversion, it should return {@code null}.
* @param payload the Object to convert
* @param headers optional headers for the message (may be {@code null})
* @return the new message, or {@code null} if the converter does not support the
* Object type or the target media type
*/
@Nullable
Message toMessage(Object payload, @Nullable MessageHeaders headers);
}