spring-integration - Spring 集成网关 "Dispatcher has no subscribers"

Question

我遇到异常 Dispatcher has no subscribers在 outboundChannel并且不知道为什么。我确信它很简单，我已经将我的代码剥离到下面的一个非常简单的示例中:

我的上下文是:

<bean id="requestService"
    class="com.sandpit.RequestService" />

<integration:channel id="inboundChannel" />

<integration:service-activator id="service"
    input-channel="inboundChannel"
    output-channel="outboundChannel"
    ref="requestService"
    method="handleRequest" />

<integration:channel id="outboundChannel" />

<integration:gateway id="gateway"
    service-interface="com.sandpit.Gateway"
    default-request-channel="inboundChannel"
    default-reply-channel="outboundChannel" />

<bean class="com.sandpit.GatewayTester">
    <property name="gateway"
        ref="gateway" />
</bean>

我的Java代码是:

public interface Gateway {

    String receive();
    void send(String message);
}

public class RequestService {

    public String handleRequest(String request) {

        return "Request received: " + request;
    }
}

public class GatewayTester implements ApplicationListener<ContextRefreshedEvent> {

    private Gateway gateway;

    public void setGateway(Gateway gateway) {

        this.gateway = gateway;
    }

    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {

        gateway.send("Hello world!");
        System.out.println("FROM SERVICE: " + gateway.receive());
    }
}

注意:断点确实告诉我 RequestService实际上正在处理请求。

Answer 1

receive()没有参数需要回复 channel 是 PollableChannel见 the documentation .

添加 <queue/>到 outboundChannel .

或者，您可以将网关方法更改为 String sendAndReceive(String in)并且一切都会按预期工作(您甚至可以完全删除 outboundChannel)。