运行 Spring 启动应用程序时出现与 bean 创建相关的错误

Question

I am learning spring boot with JPA and i have a problem when launch my app. Could somebody help me to solve this issue? Error is -

Description: Field userRepo in com.example.demo.controller.DemoController required a bean of type 'com.example.demo.repo.UserRepo' 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.example.demo.repo.UserRepo' in your configuration.

Controller

public class DemoController {
private static final String CLASS_NAME = DemoController.class.getName();
@Autowired
private UserRepo userRepo;

@Autowired
private UserServiceImpl userService;

  @PostMapping(value = "/hello", consumes = "application/json", produces = "application/json") 
  public String createUser(@RequestBody User user) {
       long count = userRepo.count();
      return "Done"; 
  }
}

repository

@Repository

public interface UserRepo extends JpaRepository<User, Integer> {    
}

Application class

@SpringBootApplication
@ComponentScan("com.example.demo*")
@EnableJpaRepositories(basePackages = {"com.example.demo*"})
@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})
public class DemoApplication {

public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
}

}

Project structure

I annotated repository with @Repository and using @Autowired on controller. Where i am doing wrong?

Answer 1

You added quite a lot annotations which aren't really needed.

Make the following changes

     DemoController.java -> Add `@Controller or @RestController` annotation
     Application.java --> Remove annotations completely

    @ComponentScan() 
    @EnableJpaRepositories()
    @EnableAutoConfiguration()

Let me know if it works.

Try.

Answer 2

You are probably missing the @EnableJpaRepositories annotation in your configuration class. This will then scan for all classes with the @Repository annotation.

Answer 3

Can you share the package structure of your project?

I doubt that component scan is unable to scan your UserRepo class.