Spring Boot应用启动失败：无法自省HystrixCircuitBreakerAutoConfiguration类

Spring Boot应用无法启动，报错信息为“Failed to introspect Class [org.springframework.cloud.netflix.hystrix.HystrixCircuitBreakerAutoConfiguration]”，完整错误栈如下：

java.lang.IllegalStateException: Error processing condition on org.springframework.cloud.openfeign.ribbon.DefaultFeignLoadBalancedConfiguration.feignClient
    at org.springframework.boot.autoconfigure.condition.SpringBootCondition.matches(SpringBootCondition.java:60)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331)
    
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95)
    
    
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    
Caused by: java.lang.IllegalStateException: Failed to introspect Class [org.springframework.cloud.netflix.hystrix.HystrixCircuitBreakerAutoConfiguration] from ClassLoader [sun.misc.Launcher$AppClassLoader@18b4aac2]
    
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:649)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1605)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:223)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getBeanNamesForType(OnBeanCondition.java:213)
    at org.springframework.boot.autoconfigure.condition.OnBeanCondition.getMatchingBeans(OnBeanCondition.java:167)
    
Caused by: java.lang.NoClassDefFoundError: org/springframework/cloud/client/circuitbreaker/CircuitBreakerFactory
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
    at java.lang.Class.getDeclaredMethods(Class.java:1975)
    org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:463)
    ... 33 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.cloud.client.circuitbreaker.CircuitBreakerFactory
    at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)

项目的Pom配置如下：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.6.RELEASE</version>

</parent>
<properties>
    <java.version>1.8</java.version>
    <spring-cloud-netflix-core.version>2.2.6.RELEASE</spring-cloud-netflix- core.version>
</properties>
<dependencies>
    <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
    <version>2.0.1.RELEASE</version>
    </dependency>
</dependencies>

问题根源是Spring Boot与Spring Cloud版本不兼容，且缺少必要的断路器依赖，具体修复步骤如下：

• 统一Spring Cloud版本，匹配Spring Boot版本
  Spring Boot 2.2.6.RELEASE对应的Spring Cloud版本为Hoxton.SR8，需通过Spring Cloud依赖管理统一版本，避免单独指定组件版本导致冲突。修改Pom配置如下：

  <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>2.2.6.RELEASE</version>
  </parent>
  
  <properties>
      <java.version>1.8</java.version>
      <spring-cloud.version>Hoxton.SR8</spring-cloud.version>
  </properties>
  
  <dependencyManagement>
      <dependencies>
          <dependency>
              <groupId>org.springframework.cloud</groupId>
              <artifactId>spring-cloud-dependencies</artifactId>
              <version>${spring-cloud.version}</version>
              <type>pom</type>
              <scope>import</scope>
          </dependency>
      </dependencies>
  </dependencyManagement>
  
  <dependencies>
      <dependency>
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-openfeign</artifactId>
      </dependency>
      <!-- 添加Hystrix依赖，解决CircuitBreakerFactory缺失问题 -->
      <dependency>
          <groupId>org.springframework.cloud</groupId>
          <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
      </dependency>
  </dependencies>
  

• 清理并重新构建项目
  执行mvn clean install清理本地仓库的冲突依赖，重新下载匹配版本后，重启应用验证启动状态。

补充说明：
CircuitBreakerFactory是Spring Cloud断路器抽象层类，需引入spring-cloud-starter-netflix-hystrix依赖提供具体实现；通过spring-cloud-dependencies统一管理版本是避免Spring Cloud组件版本冲突的最佳实践。

内容的提问来源于stack exchange，提问作者user19373833