通过带有 Spring Integration 的 TCP 连接“只写”

Question

我正在使用int-ip:tcp-connection-factory 和int-ip:tcp-outbound-gateway 与外部服务器通信。服务器提供的大多数服务的协议都遵循标准的请求-响应样式……效果很好。但是，在某些情况下，我只需要发送一个请求，而无需响应。

我的问题是，如何配置我的频道和连接，以便我可以指定是否等待响应？目前我找不到方法，即使我不期待响应，Spring 也会在发送请求后阻塞。

编辑： 正如建议的那样，我使用了tcp-outbound-channel-adapter。我的配置文件只有以下内容：

<int:channel id="requestChannel" />

<int-ip:tcp-outbound-channel-adapter
    channel="requestChannel" connection-factory="client" />

<int-ip:tcp-connection-factory id="client"
    type="client" host="smtp.gmail.com" port="587" single-use="false"
    so-timeout="10000" />

这是我的主要课程：

public final class Main {

    private static final Logger LOGGER = Logger.getLogger(Main.class);

    public static void main(final String... args) throws IOException {
        LOGGER.debug("entered main()...");

        final AbstractApplicationContext context = new ClassPathXmlApplicationContext(
                "classpath:*-context.xml");

        MessageChannel requestChannel = context.getBean("requestChannel", MessageChannel.class);
        requestChannel.send(MessageBuilder.withPayload("QUIT").build());

        LOGGER.debug("exiting main()...");
    }

}

最后这是我在日志中得到的：

11:57:15.877 INFO  [main][com.together.email.Main] entered main()...
11:57:16.295 INFO  [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'errorChannel' has been explicitly defined. Therefore, a default PublishSubscribeChannel will be created.
11:57:16.295 INFO  [main][org.springframework.integration.config.xml.DefaultConfiguringBeanFactoryPostProcessor] No bean named 'taskScheduler' has been explicitly defined. Therefore, a default ThreadPoolTaskScheduler will be created.
11:57:16.480 INFO  [main][org.springframework.integration.ip.tcp.connection.TcpNetClientConnectionFactory] started client
11:57:16.480 INFO  [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {ip:tcp-outbound-channel-adapter} as a subscriber to the 'requestChannel' channel
11:57:16.480 INFO  [main][org.springframework.integration.channel.DirectChannel] Channel 'requestChannel' has 1 subscriber(s).
11:57:16.480 INFO  [main][org.springframework.integration.endpoint.EventDrivenConsumer] started org.springframework.integration.config.ConsumerEndpointFactoryBean#0
11:57:16.480 INFO  [main][org.springframework.integration.endpoint.EventDrivenConsumer] Adding {logging-channel-adapter:_org.springframework.integration.errorLogger} as a subscriber to the 'errorChannel' channel
11:57:16.481 INFO  [main][org.springframework.integration.channel.PublishSubscribeChannel] Channel 'errorChannel' has 1 subscriber(s).
11:57:16.481 INFO  [main][org.springframework.integration.endpoint.EventDrivenConsumer] started _org.springframework.integration.errorLogger
11:57:16.509 DEBUG [main][org.springframework.integration.channel.DirectChannel] preSend on channel 'requestChannel', message: [Payload=QUIT][Headers={timestamp=1381021036509, id=860ebe82-06c6-4393-95c7-0ece1a0a0e5d}]
11:57:16.509 DEBUG [main][org.springframework.integration.ip.tcp.TcpSendingMessageHandler] org.springframework.integration.ip.tcp.TcpSendingMessageHandler#0 received message: [Payload=QUIT][Headers={timestamp=1381021036509, id=860ebe82-06c6-4393-95c7-0ece1a0a0e5d}]
11:57:16.509 DEBUG [main][org.springframework.integration.ip.tcp.connection.TcpNetClientConnectionFactory] Opening new socket connection to smtp.gmail.com:587
11:57:16.745 DEBUG [main][org.springframework.integration.ip.tcp.connection.TcpNetConnection] New connection smtp.gmail.com:587:550c9b68-10a0-442d-b65d-d25d28df306b
11:57:16.748 DEBUG [main][org.springframework.integration.ip.tcp.TcpSendingMessageHandler] Got Connection smtp.gmail.com:587:550c9b68-10a0-442d-b65d-d25d28df306b
11:57:16.749 DEBUG [pool-1-thread-1][org.springframework.integration.ip.tcp.connection.TcpNetConnection] TcpListener exiting - no listener and not single use
11:57:16.750 DEBUG [main][org.springframework.integration.ip.tcp.connection.TcpNetConnection] Message sent [Payload=QUIT][Headers={timestamp=1381021036509, id=860ebe82-06c6-4393-95c7-0ece1a0a0e5d}]
11:57:16.750 DEBUG [main][org.springframework.integration.channel.DirectChannel] postSend (sent=true) on channel 'requestChannel', message: [Payload=QUIT][Headers={timestamp=1381021036509, id=860ebe82-06c6-4393-95c7-0ece1a0a0e5d}]
11:57:16.751 INFO  [main][com.together.email.Main] exiting main()...

我已将 Spring 的日志记录设置为调试级别，以便为您提供更多详细信息。从日志的最后一行可以看出，我的 main 退出了。然而，不幸的是，应用程序并没有因为[pool-1-thread-1] 继续运行而终止。只要在requestChannel 上调用send，这个线程就会出现。知道这里发生了什么吗？

[在本例中，我将在应用程序连接到 Google 后立即发送 SMTP QUIT 消息。在实践中，我实际上不会从 QUIT 开始。例如，一开始我可能会从 HELO 消息开始。我尝试使用tcp-inbound-channel-adapter 来获取消息响应，效果很好。问题在于我不希望回复的消息。]

Answer 1

所以，我建议你向<int-ip:tcp-connection-factory> 注入一些“假”task-executor：

public class NullExecutor implements Executor {

    public void execute(Runnable command) {}
}

在这种情况下，您来自 AbstractClientConnectionFactory#obtainConnection() 的连接不会被配置（运行）以从套接字读取。

但是，System.exit(0); 作为 ma​​in 的最后一行就足够了。在这种情况下，所有线程都将被终止，如果它们不是守护进程的话。