java - Feign 客户端、Spring Boot 应用程序和 rx/Observable 类未找到错误

Question

一些背景:我构建了两个被设计为微服务的 Spring Boot 应用程序。第一个应用程序(时间表提供)是一个 RESTful 服务，为另一个应用程序(时间表检查器)提供数据。因此，两种服务之间存在简单的生产者-消费者关系。

遵循 setting up microservice discovery using Eureka 的 Spring 教程后，我有一个可以成功启动的 Eureka 服务注册表，并且计划提供和计划检查器服务已成功向 Eureka 服务注册表注册(通过检查 Eureka 服务的登陆页面进行验证)。

我现在尝试set-up microservice communication using Feign Client ，即我在计划检查器服务中定义了一个 Feign Client 接口(interface)，该接口(interface)应该使该服务能够通过 Eureka 端点解析联系计划提供服务，并使用来自计划提供服务的数据。但是，在将 Eureka 发现服务和计划供应服务作为 Spring Boot 应用程序启动后，在尝试将计划检查器服务作为 Spring Boot 应用程序运行时，我不断收到以下错误:

java.lang.ClassNotFoundException: rx.Observable

这是错误链的根本原因，从上到下读取为:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleCheckerController': Unsatisfied dependency expressed through field 'scheduleRepository'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleRepositoryImpl': Unsatisfied dependency expressed through field 'scheduleService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleServiceImpl': Unsatisfied dependency expressed through field 'scheduleDatabaseClient'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.greensill.emailarrivalmonitoring.client.ScheduleDatabaseFeignClient': FactoryBean threw exception on object creation; nested exception is java.lang.NoClassDefFoundError: rx/Observable
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1225) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:552) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) ~[spring-context-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:761) [spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:371) [spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1186) [spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1175) [spring-boot-1.4.3.RELEASE.jar:1.4.3.RELEASE]
at com.greensill.emailarrivalmonitoring.EmailArrivalMonitoringApplication.main(EmailArrivalMonitoringApplication.java:18) [classes/:na]

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleRepositoryImpl': Unsatisfied dependency expressed through field 'scheduleService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleServiceImpl': Unsatisfied dependency expressed through field 'scheduleDatabaseClient'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.greensill.emailarrivalmonitoring.client.ScheduleDatabaseFeignClient': FactoryBean threw exception on object creation; nested exception is java.lang.NoClassDefFoundError: rx/Observable
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1225) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:552) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1136) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1064) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 19 common frames omitted

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'scheduleServiceImpl': Unsatisfied dependency expressed through field 'scheduleDatabaseClient'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.greensill.emailarrivalmonitoring.client.ScheduleDatabaseFeignClient': FactoryBean threw exception on object creation; nested exception is java.lang.NoClassDefFoundError: rx/Observable
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1225) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:552) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1136) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1064) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 32 common frames omitted

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.greensill.emailarrivalmonitoring.client.ScheduleDatabaseFeignClient': FactoryBean threw exception on object creation; nested exception is java.lang.NoClassDefFoundError: rx/Observable
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:175) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:103) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1626) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:254) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.addCandidateEntry(DefaultListableBeanFactory.java:1297) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1263) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1099) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1064) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 45 common frames omitted

Caused by: java.lang.NoClassDefFoundError: rx/Observable
at feign.hystrix.HystrixDelegatingContract.parseAndValidatateMetadata(HystrixDelegatingContract.java:42) ~[feign-hystrix-9.3.1.jar:na]
at feign.ReflectiveFeign$ParseHandlersByName.apply(ReflectiveFeign.java:146) ~[feign-core-9.3.1.jar:na]
at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:53) ~[feign-core-9.3.1.jar:na]
at feign.Feign$Builder.target(Feign.java:209) ~[feign-core-9.3.1.jar:na]
at org.springframework.cloud.netflix.feign.HystrixTargeter.target(HystrixTargeter.java:48) ~[spring-cloud-netflix-core-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.cloud.netflix.feign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:146) ~[spring-cloud-netflix-core-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.cloud.netflix.feign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:167) ~[spring-cloud-netflix-core-1.2.3.RELEASE.jar:1.2.3.RELEASE]
at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:168) ~[spring-beans-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 55 common frames omitted

Caused by: java.lang.ClassNotFoundException: rx.Observable
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_121]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_121]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[na:1.8.0_121]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_121]
... 63 common frames omitted

据我所知，该错误似乎是由于缺少对 RxJava 的依赖引起的。这会导致 rx.Observable 类不可用。但是，添加RxJava dependency后到计划检查器服务的 pom.xml 并运行 mvn clean install，上面详细说明的错误仍然存​​在。我不确定如何解决这个问题，因为网上似乎没有任何资源可以专门解决这个问题。我构建的两个微服务中的相关类/文件应该能够实现我期望的行为(计划检查器服务通过计划供应服务中定义的 REST 端点使用计划供应服务数据):

安排提供服务

主应用类

@SpringBootApplication
@EnableEurekaClient
public class EmailArrivalScheduleServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(EmailArrivalScheduleServiceApplication.class, args);
    }
}

调度提供程序 REST Controller

@RestController
public class ScheduleDatabaseController {

    @Autowired
    private ScheduleDatabaseService scheduleDatabaseService;

    @RequestMapping(value="/schedules", method=RequestMethod.GET)
    public Iterable<Schedule> getSchedules(){
        return this.scheduleDatabaseService.getSchedules();
    }
}

bootstrap.yml

spring:
  application:
    name: email-arrival-schedule-service

eureka:
  instance:
    prefer-ip-address: true
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

日程检查服务

主应用类

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@EnableScheduling
@IntegrationComponentScan
public class EmailArrivalMonitoringApplication {

    public static void main(String args[]) {
        SpringApplication.run(EmailArrivalMonitoringApplication.class, args);
    }
}

假客户端界面

@FeignClient("email-arrival-schedule-service")
public interface ScheduleDatabaseFeignClient {

    @RequestMapping(method = RequestMethod.GET, value = "/schedules")
    public List<Schedule> getSchedules();
}

安排供应消费者

@Service
public class ScheduleServiceImpl implements ScheduleService {

    @Autowired
    private ScheduleDatabaseFeignClient scheduleDatabaseClient;

    @Override
    public List<Schedule> getSchedules() {
        return scheduleDatabaseClient.getSchedules();
    }
}

bootstrap.yml

spring:
  application:
    name: email-arrival-monitoring-service

eureka:
  instance:
    prefer-ip-address: true
  client:
    serviceUrl:
      defaultZone: http://localhost:8761/eureka/

pom.xml(仅依赖项)

<dependencies>
    <dependency>
        <groupId>${project.parent.groupId}</groupId>
        <artifactId>email-arrival-dto</artifactId>
        <version>${project.parent.version}</version>
    </dependency>

    <dependency>
        <groupId>io.reactivex.rxjava2</groupId>
        <artifactId>rxjava</artifactId>
        <version>2.0.8</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-integration</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-ribbon</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-file</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-java-dsl</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-mail</artifactId>
    </dependency>

    <dependency>
        <groupId>com.icegreen</groupId>
        <artifactId>greenmail-spring</artifactId>
        <version>1.5.3</version>
    </dependency>

    <dependency>
        <groupId>org.hamcrest</groupId>
        <artifactId>hamcrest-all</artifactId>
        <scope>test</scope>
    </dependency>

</dependencies>

Answer 1

准备好这个问题后，我在 2 位同事的帮助下解决了这个问题。修改内容如下:

1. RxJava 被许多 Spring Boot 依赖项声明为依赖项，因此应排除这些声明的 RxJava 依赖项以防止冲突。
2. 似乎需要特定版本的 RxJava，我已包含对 1.0.12 版本的依赖项，这似乎是解决问题的一部分。
3. 包含我正在构建的服务的项目是一个多模块 Maven 项目，因此有一个父 pom.xml 文件。在此文件中，存在对 org.springframework.cloud.spring-cloud-dependency.pom.xml 的依赖项。此依赖项的版本曾设置为 Camden.SR3，但现在定义为 Dalston.RELEASE。将版本更改回 Camden.SR3 似乎会导致我原来问题中定义的错误。
4. this spring-cloud-netflix class 执行了一些 Bean 自动配置。这似乎导致了提到的 java.lang.ClassNotFoundException: rx.Observable 问题。要解决此问题，请将以下注释添加到包含要设置的 Feign Client 的服务的应用程序类:@EnableAutoConfiguration(exclude = {RxJavaAutoConfiguration.class})

总而言之，要进行的更改如下。关于计划检查器服务 pom.xml (不是整个项目的父 pom)，所有其他代码仍然与我原来的问题中的详细信息相同:

调度检查器父级

pom.xml

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>Dalston.RELEASE</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

日程检查服务

pom.xml

<dependencies>
    <dependency>
        <groupId>io.reactivex</groupId>
        <artifactId>rxjava</artifactId>
        <version>1.0.12</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-ribbon</artifactId>
        <exclusions>
            <exclusion>
                <groupId>io.reactivex</groupId>
                <artifactId>rxjava</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
        <exclusions>
            <exclusion>
                <groupId>io.reactivex</groupId>
                <artifactId>rxjava</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-feign</artifactId>
        <exclusions>
            <exclusion>
                <groupId>io.reactivex</groupId>
                <artifactId>rxjava</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

应用程序类

@SpringBootApplication
@EnableEurekaClient
@EnableFeignClients
@EnableScheduling
@IntegrationComponentScan
@EnableAutoConfiguration(exclude = {RxJavaAutoConfiguration.class})
public class EmailArrivalMonitoringApplication {

    public static void main(String args[]) {
        SpringApplication.run(EmailArrivalMonitoringApplication.class, args);
    }
}

最后，可能的情况是:在您的项目上运行 mvn clean install 后(正如我所做的那样)，并启动 Eureka 发现服务和应该通信的服务(在我的例子中，调度提供服务和调度检查服务)，包含 Feign Client 的服务会抛出异常。我不确定为什么会发生这种情况，但是，如果您终止服务并再次启动它，一切都会正常工作。

我希望这会有所帮助，我花了大约 2 天的时间来纠正这个问题，我会敦促 Spring Boot 的相关人员快速相应地更新他们的文档!