spring-integration - 在初始化方法中使用 channel 时，Spring集成 'Dispatcher has no subscribers'

Question

尝试在Spring bean的init-method中将消息发布到 channel 时出现“Dispatcher没有订阅者”错误。请看下面的例子:

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:rmi="http://www.springframework.org/schema/integration/rmi"
    xmlns:int="http://www.springframework.org/schema/integration"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/integration
        http://www.springframework.org/schema/integration/spring-integration.xsd
        http://www.springframework.org/schema/integration/rmi
        http://www.springframework.org/schema/integration/rmi/spring-integration-rmi.xsd">

    <bean id="currencyService" class="com.demo.CurrencyService" init-method="init"/>

    <int:channel id="currencyChannel" />
    <int:channel id="currencyReplyChannel">
        <int:queue/>
    </int:channel>
    <rmi:outbound-gateway id="currencyServiceGateway"
        request-channel="currencyChannel" remote-channel="currencyServiceChannel"
        reply-channel="currencyReplyChannel" host="localhost" port="2197" />
</beans>

Spring 托管bean:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.integration.Message;
import org.springframework.integration.MessageChannel;
import org.springframework.integration.core.MessagingTemplate;
import org.springframework.integration.core.PollableChannel;
import org.springframework.integration.message.GenericMessage;

public class CurrencyService {

    @Autowired
    private MessageChannel currencyChannel;

    @Autowired
    private PollableChannel currencyReplyChannel;

    private CurrencyListBO currencyListBO;

    public CurrencyListBO getCurrencyList() {
        return currencyListBO;
    }

    public void init() {
        CurrencyIN request = new CurrencyIN();
        request.setChannelCode("RMW");
        request.setTransactionType(CurrencyIN.TransactionType.currencyLoaderService
                .toString());
        GenericMessage<IRequestBO> message = new GenericMessage<IRequestBO>(
                request);
        MessagingTemplate template = new MessagingTemplate();
        template.send(currencyChannel, message);
        Message<CurrencyListBO> reply = template.receive(currencyReplyChannel);
        currencyListBO = reply.getPayload();
    }
}

如果在第一次调用后初始化了currencyListBO而不是init方法，则一切正常。

public CurrencyListBO getCurrencyList() {
    if(currencyListBO == null) {
        init();
    }
    return currencyListBO;
}

请让我知道第一种方法的问题。

Answer 1

在实例化您的bean之后但在关联其余上下文之前(在这种情况下，在将RMI适配器预订到 channel 之前)将调用init/@ PostConstruct方法。

您需要等待，直到上下文完全刷新为止。

做到这一点的一种方法是实现

ApplicationListener<ContextRefreshedEvent>

然后把你的代码放进去

public void onApplicationEvent(ContextRefreshedEvent event)

上下文完全连接后将调用该方法。