springboot available: expected at least 1 bean which qualifies as autowire candidate奇葩问题

Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'apiUserController': Unsatisfied dependency expressed through field 'apiMutiHttpClientUtil'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.crt.openapi.utils.ApiMutiHttpClientUtil' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Description:

Field apiMutiHttpClientUtil in com.crt.openapi.apiinterface.controller.base.CommonController required a bean of type 'com.crt.openapi.utils.ApiMutiHttpClientUtil' that could not be found.

The injection point has the following annotations:
- @org.springframework.beans.factory.annotation.Autowired(required=true)

Action:

Consider defining a bean of type 'com.crt.openapi.utils.ApiMutiHttpClientUtil' in your configuration.

总是提示无法注入Service或者Dao中的Bean！

后来经研究发现，SpringBoot项目的Bean装配默认规则是根据Application类所在的包位置从上往下扫描！

“Application类”是指SpringBoot项目入口类。这个类的位置很关键：

如果Application类所在的包为：com.demo.module，则只会扫描com.demo.module包及其所有子包，如果service或dao所在包不在com.demo.module及其子包下，则不会被扫描！

所以需在application启动类中加上

@MapperScan("com.*.dao")//加上你项目的dao或service所在文件位置即可

@SpringBootApplication