SSM商城系統開發筆記-問題02- Error creating bean with name 'userController'

Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException:
 Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'userService';
 nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: 
 No qualifying bean of type 'com.boron.service.UserService' available: expected at least 1 bean which qualifies as autowire candidate. 
Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

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原因：service層沒有加注解
在搭spring mvc框架時，ide不會報錯但會有編譯錯誤的幾個注意事項：
1.controller 加注解

@RestController
@RequestMapping("/user")

2.service加注解

@Service
@Autowired

3.dao 加注解和實現接口
@Param("")