spring ChannelInterceptor 源码

spring ChannelInterceptor 代码

文件路径：/spring-messaging/src/main/java/org/springframework/messaging/support/ChannelInterceptor.java

/*
 * 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;

/**
 * Interface for interceptors that are able to view and/or modify the
 * {@link Message Messages} being sent-to and/or received-from a
 * {@link MessageChannel}.
 *
 * @author Mark Fisher
 * @author Rossen Stoyanchev
 * @since 4.0
 * @see Message
 * @see MessageChannel
 */
public interface ChannelInterceptor {

	/**
	 * Invoked before the Message is actually sent to the channel.
	 * This allows for modification of the Message if necessary.
	 * If this method returns {@code null} then the actual
	 * send invocation will not occur.
	 */
	@Nullable
	default Message<?> preSend(Message<?> message, MessageChannel channel) {
		return message;
	}

	/**
	 * Invoked immediately after the send invocation. The boolean
	 * value argument represents the return value of that invocation.
	 */
	default void postSend(Message<?> message, MessageChannel channel, boolean sent) {
	}

	/**
	 * Invoked after the completion of a send regardless of any exception that
	 * have been raised thus allowing for proper resource cleanup.
	 * <p>Note that this will be invoked only if {@link #preSend} successfully
	 * completed and returned a Message, i.e. it did not return {@code null}.
	 * @since 4.1
	 */
	default void afterSendCompletion(
			Message<?> message, MessageChannel channel, boolean sent, @Nullable Exception ex) {
	}

	/**
	 * Invoked as soon as receive is called and before a Message is
	 * actually retrieved. If the return value is 'false', then no
	 * Message will be retrieved. This only applies to PollableChannels.
	 */
	default boolean preReceive(MessageChannel channel) {
		return true;
	}

	/**
	 * Invoked immediately after a Message has been retrieved but before
	 * it is returned to the caller. The Message may be modified if
	 * necessary; {@code null} aborts further interceptor invocations.
	 * This only applies to PollableChannels.
	 */
	@Nullable
	default Message<?> postReceive(Message<?> message, MessageChannel channel) {
		return message;
	}

	/**
	 * Invoked after the completion of a receive regardless of any exception that
	 * have been raised thus allowing for proper resource cleanup.
	 * <p>Note that this will be invoked only if {@link #preReceive} successfully
	 * completed and returned {@code true}.
	 * @since 4.1
	 */
	default void afterReceiveCompletion(@Nullable Message<?> message, MessageChannel channel,
			@Nullable Exception ex) {
	}

}

相关信息

spring 源码目录

相关文章

spring AbstractHeaderMapper 源码

spring AbstractMessageChannel 源码

spring AbstractSubscribableChannel 源码

spring ErrorMessage 源码

spring ExecutorChannelInterceptor 源码

spring ExecutorSubscribableChannel 源码

spring GenericMessage 源码

spring HeaderMapper 源码

spring IdTimestampMessageHeaderInitializer 源码

spring ImmutableMessageChannelInterceptor 源码