spring-integration通道

消息通道

顶层接口，返回true即为发送成功，返回false即为发送失败或者超时。

public interface MessageChannel {

    boolean send(Message message);

    boolean send(Message message, long timeout);
}

轮询接口，返回一个消息，超时或者打断返回null。会缓冲消息。

public interface PollableChannel extends MessageChannel {

    Message<?> receive();

    Message<?> receive(long timeout);

}

订阅接口，直接发送消息到处理器。不轮询，不会缓冲消息。

public interface SubscribableChannel extends MessageChannel {

    boolean subscribe(MessageHandler handler);

    boolean unsubscribe(MessageHandler handler);

}

通道实现，实现了上述接口的主要通道有：

PublishSubscribeChannel
QueueChannel
PriorityChannel
RendezvousChannel
DirectChannel
ExecutorChannel
FluxMessageChannel

拦截器，拦截通道的消息，加入自定义过程

public interface ChannelInterceptor {
    Message<?> preSend(Message<?> message, MessageChannel channel);

    void postSend(Message<?> message, MessageChannel channel, boolean sent);

    void afterSendCompletion(Message<?> message, MessageChannel channel, boolean sent, Exception ex);

    boolean preReceive(MessageChannel channel);

    Message<?> postReceive(Message<?> message, MessageChannel channel);

    void afterReceiveCompletion(Message<?> message, MessageChannel channel, Exception ex);
}

通道添加拦截器
channel.addInterceptor(someChannelInterceptor);

消息模板，提供非倾入式的消息分发接口

MessagingTemplate template = new MessagingTemplate();

Message reply = template.sendAndReceive(someChannel, new GenericMessage("test"));

还有一些其他的交互方法

public boolean send(final MessageChannel channel, final Message<?> message) { ...
}

public Message<?> sendAndReceive(final MessageChannel channel, final Message<?> request) { ...
}

public Message<?> receive(final PollableChannel<?> channel) { ...
}

配置消息通道，各种通道的个性化配置