解决java.lang.IllegalStateException: Failed to load ApplicationContext

 When working on a project today, I encountered the following error

java.lang.IllegalStateException: Failed to load ApplicationContext

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userServiceImpl': Injection of resource dependencies failed;

The meaning of this sentence is the reason: org.springframework.beans.factory. BeanCreationException: Error creating bean named 'userServiceImpl': Failed to inject resource dependency;

First, I checked that the @Servive annotation was added to userServiceImpl and @Resource was added 

 Then I wrote the test method in UserServiceTest and injected @SpringBootTest and

@Resource
private UserService userService;

 

However, the problem is still not resolved, and it took half an hour to figure it out.

No Mapper annotation added

Adding mapper annotations to the startup class solves the problem