The IntegrationFlow can start from the service interface that provides a GatewayProxyFactoryBean component, as the following example shows:spring-doc.cn

public interface ControlBusGateway {

    void send(String command);
}

...

@Bean
public IntegrationFlow controlBusFlow() {
    return IntegrationFlow.from(ControlBusGateway.class)
            .controlBus()
            .get();
}

All the proxy for interface methods are supplied with the channel to send messages to the next integration component in the IntegrationFlow. You can mark the service interface with the @MessagingGateway annotation and mark the methods with the @Gateway annotations. Nevertheless, the requestChannel is ignored and overridden with that internal channel for the next component in the IntegrationFlow. Otherwise, creating such a configuration by using IntegrationFlow does not make sense.spring-doc.cn

By default, a GatewayProxyFactoryBean gets a conventional bean name, such as [FLOW_BEAN_NAME.gateway]. You can change that ID by using the @MessagingGateway.name() attribute or the overloaded IntegrationFlow.from(Class<?> serviceInterface, Consumer<GatewayProxySpec> endpointConfigurer) factory method. Also, all the attributes from the @MessagingGateway annotation on the interface are applied to the target GatewayProxyFactoryBean. When annotation configuration is not applicable, the Consumer<GatewayProxySpec> variant can be used for providing appropriate option for the target proxy. This DSL method is available starting with version 5.2.spring-doc.cn

With Java 8, you can even create an integration gateway with the java.util.function interfaces, as the following example shows:spring-doc.cn

@Bean
public IntegrationFlow errorRecovererFlow() {
    return IntegrationFlow.from(Function.class, (gateway) -> gateway.beanName("errorRecovererFunction"))
            .<Object>handle((p, h) -> {
                throw new RuntimeException("intentional");
            }, e -> e.advice(retryAdvice()))
            .get();
}

That errorRecovererFlow can be used as follows:spring-doc.cn

@Autowired
@Qualifier("errorRecovererFunction")
private Function<String, String> errorRecovererFlowGateway;