環(huán)境

dubbo版本： 2.7.3

springCloud版本： 2.2.0

復(fù)現(xiàn)步驟

當使用@Service注解注入dubbo provider到Spring容器中時，在dubbo provider的bean對象里依賴SpringCloud的bean時硫朦，觸發(fā)報錯烈菌，應(yīng)用報錯無法啟動花履！

dubbo provider bean

@Service(registry = "dubbo-registry", interfaceClass = DubboProvideFacade.class)
public class DubboProviderServiceImpl implements DubboProvideFacade {
  @Resource
    private FeignClient feignClient;
  ······
}

SpringCloud Client

@FeignClient(name = "feignClient", url = "${feign.client.config.url}", configuration = FeignClientInterceptor.class)
public interface FeignClient {
    ······
}

報錯

報錯圖片

Caused by: java.lang.IllegalStateException: <dubbo:service interface="" /> interface not allow null!
    at org.apache.dubbo.config.ServiceConfig.checkAndUpdateSubConfigs(ServiceConfig.java:297)
    at org.apache.dubbo.config.ServiceConfig.export(ServiceConfig.java:358)
    at org.apache.dubbo.config.spring.ServiceBean.export(ServiceBean.java:327)
    at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:105)
    at org.apache.dubbo.config.spring.ServiceBean.onApplicationEvent(ServiceBean.java:51)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:402)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:408)
    at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:359)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:896)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:552)
    at org.springframework.cloud.context.named.NamedContextFactory.createContext(NamedContextFactory.java:136)
    at org.springframework.cloud.context.named.NamedContextFactory.getContext(NamedContextFactory.java:101)
    at org.springframework.cloud.context.named.NamedContextFactory.getInstance(NamedContextFactory.java:145)
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.get(FeignClientFactoryBean.java:224)
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.feign(FeignClientFactoryBean.java:85)
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:261)
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:251)
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:171)
    ... 142 common frames omitted

原因

這個錯誤是由 Spring Cloud Feign 設(shè)計引起的济瓢，每個@FeignClient都會生成一個帶有新子 Spring 的 Feign 代理妹卿，該子 SpringApplicationContext可能會在其 parent 之前刷新ApplicationContext蔑鹦。如果有注解@Service的 Dubbo 服務(wù) bean 被子上下文掃描到箕宙，這個 DubboServiceBean也會被初始化，并且不能保證其依賴的 Spring bean 在那個時候已經(jīng)準備好

解決方式

方式一（已驗證）

將FeignClient使用ApplicationContextAware進行獲取

首先寫一個SpringBean獲取工具類

@Component
public class SpringBeanUtil implements ApplicationContextAware {
    private static ApplicationContext appContext;

    private static boolean hasBean(String name){
        return appContext.containsBean(name);
    }

    public static Object getBeanByName(String name) throws BeansException {
        return appContext.getBean(name);
    }

    public static Object getBeanByType(Class requiredType) throws BeansException {
        return appContext.getBean(requiredType);
    }

    public static Object getBeanIfPresent(String name){
        if(hasBean(name)){
            return getBeanByName(name);
        }
        return null;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        setAppContext(applicationContext);
    }

    private static synchronized void setAppContext(ApplicationContext appContext) {
        SpringBeanUtil.appContext = appContext;
    }
}

通過Util獲取FeignClient而不是Spring注入的方式

FeignClient client = SpringContextUtils.getBean(FeignClient.class)

方式二

升級dubbo版本至2.7.9

據(jù)說在2.7.9解決了改問題

方式三

一個不完美的解決方法是，讓FeignClient以來注入的方式進行注入

@Service(registry = "dubbo-registry", interfaceClass = DubboProvideFacade.class)
public class DubboProviderServiceImpl implements DubboProvideFacade {
  @Resource
  @Lazy
    private FeignClient feignClient;
  ······
}