报错：Consider defining a bean of type 'xxx' in your configuration.

今天在做多模块项目demo时启动子模块时报错

2018-09-17 16:26:42.756  WARN 8640 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'testController': Unsatisfied dependency expressed through field 'commonMethod'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.example.demo1.helper.CommonMethod' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2018-09-17 16:26:42.758  INFO 8640 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2018-09-17 16:26:42.861  INFO 8640 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-09-17 16:26:43.028 ERROR 8640 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Field commonMethod in com.example.demo2.controller.TestController required a bean of type 'com.example.demo1.helper.CommonMethod' that could not be found.

Action:
Consider defining a bean of type 'com.example.demo1.helper.CommonMethod' in your configuration.
Process finished with exit code 1

错误原因和解决方案也给出了提示：expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

原因分析：在默认情况下使用 @Autowired 注释进行自动注入时，Spring 容器中匹配的候选 Bean 数目必须有且仅有一个。当找不到一个匹配的 Bean 时，Spring 容器将抛出 异常，并指出必须至少拥有一个匹配的 Bean。

所以只要将 @Autowired 改成 @Autowired(required=true) 就可以了