java - 如何捕获 spring-integration 套接字服务器中的错误？

Question

我有以下工作套接字服务器配置，并且希望在发生任何异常时添加一个处理程序，例如在读取消息期间在反序列化器内。

因此我添加了一个@ServiceActivator(inputChannel = "errorChannel")。但该方法从未被调用。为什么？

@MessageEndpoint
public class SocketEndpoint {
    @ServiceActivator(inputChannel = "mainChannel")
    public String handleMessage(String message) {
        return "normal response";

    }

    @ServiceActivator(inputChannel = "errorChannel")
    public String handleError(MessagingException message) {
        //TODO this is never invoked!
        return "some error";
    }
}

@Bean
public TcpInboundGateway mainGateway(
        @Qualifier("tcpFactory") TcpConnectionFactoryFactoryBean factory,
        @Qualifier("mainChannel") MessageChannel mainChannel,
        @Qualifier("errorChannel") MessageChannel errorChannel) throws Exception {
    TcpInboundGateway g = new TcpInboundGateway();
    g.setConnectionFactory(factory.getObject());
    g.setRequestChannel(mainChannel);
    g.setErrorChannel(errorChannel);
    return g;
}

@Bean
public TcpConnectionFactoryFactoryBean fact() {
   TcpConnectionFactoryFactoryBean f = new TcpConnectionFactoryFactoryBean();
   f.setType("server");
   //....
   f.setDeserializer(new MyDeserializer());
   return f;
}

class MyDeserializer implements Deserializer<String> {
    @Override
    public String deserialize(InputStream inputStream)
            throw new RuntimeException("catch me in error-channel");
    }
}

Answer 1

throw new RuntimeException("catch me in error-channel");

它无法进入错误 channel ，因为还没有消息(发送到错误 channel 的消息是下游处理失败的消息)。

标准反序列化器(扩展 AbstractByteArraySerializer )发布 TcpDeserializationExceptionEvent当反序列化失败时。请参阅ByteArrayCrLfSerializer举个例子:

https://github.com/spring-projects/spring-integration/blob/master/spring-integration-ip/src/main/java/org/springframework/integration/ip/tcp/serializer/ByteArrayCrLfSerializer.java#L78

public int fillToCrLf(InputStream inputStream, byte[] buffer) throws IOException {
    int n = 0;
    int bite;
    if (logger.isDebugEnabled()) {
        logger.debug("Available to read: " + inputStream.available());
    }
    try {
         ...
    }
    catch (SoftEndOfStreamException e) {
        throw e;
    }
    catch (IOException e) {
        publishEvent(e, buffer, n);
        throw e;
    }
    catch (RuntimeException e) {
        publishEvent(e, buffer, n);
        throw e;
    }
}

参见the documentation 。 Deserializer需要是一个 bean，这样它才能获得事件发布者。

然后您可以使用 ApplicationListener< TcpDeserializationExceptionEvent> 监听事件或@EventListener方法。