org.springframework.messaging.support.ExecutorChannelInterceptor Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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.support;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHandler;
/**
* An extension of {@link ChannelInterceptor} with callbacks to intercept the
* asynchronous sending of a {@link org.springframework.messaging.Message} to
* a specific subscriber through an {@link java.util.concurrent.Executor}.
* Supported on {@link org.springframework.messaging.MessageChannel}
* implementations that can be configured with an {@code Executor}.
*
* @author Rossen Stoyanchev
* @since 4.1
* @see Message
* @see MessageChannel
* @see MessageHandler
*/
public interface ExecutorChannelInterceptor extends ChannelInterceptor {
/**
* Invoked inside the {@link Runnable} submitted to the Executor just before
* calling the target MessageHandler to handle the message. Allows for
* modification of the Message if necessary or when {@code null} is returned
* the MessageHandler is not invoked.
* @param message the message to be handled
* @param channel the channel on which the message was sent to
* @param handler the target handler to handle the message
* @return the input message, or a new instance, or {@code null}
*/
@Nullable
default Message beforeHandle(Message message, MessageChannel channel, MessageHandler handler) {
return message;
}
/**
* Invoked inside the {@link Runnable} submitted to the Executor after calling
* the target MessageHandler regardless of the outcome (i.e. Exception raised
* or not) thus allowing for proper resource cleanup.
* Note that this will be invoked only if beforeHandle successfully completed
* and returned a Message, i.e. it did not return {@code null}.
* @param message the message handled
* @param channel the channel on which the message was sent to
* @param handler the target handler that handled the message
* @param ex any exception that may been raised by the handler
*/
default void afterMessageHandled(Message message, MessageChannel channel, MessageHandler handler,
@Nullable Exception ex) {
}
}