Spring boot @Autowired can't initialise class

Question

I have following class as:-

@SpringBootApplication
@ComponentScan("com.ma.demospringboot")
public class DemoSpringBootApp {
   public static void main(String[] args) {
      SpringApplication.run(DemoSpringBootApp.class, args);
   }
}

I have following class as:-

@Service
public class TopicService {
    // if I comment out following autowired, then it is ok.
    @Autowired
    private TopicRepository topicRepository; 
}

I have following interface as:-

public interface TopicRepository extends  CrudRepository<Topic, String> {
}

I have following class as:-

@Entity 
public class Topic {
    @Id
    private String id;
    private String name;
    private String description;

    public Topic() {
    }
}

I got following error when try to execute:-

---

APPLICATION FAILED TO START

---

Description:

Field topicRepository in com.ma.demospringboot.service.TopicService required a bean of type 'com.ma.demospringboot.repository.TopicRepository' that could not be found.

Action:

Consider defining a bean of type 'com.ma.demospringboot.repository.TopicRepository' in your configuration.

Answer 1

Spring container is not finding your repository classes during the scan, add @EnableJpaRepositories to explicitly specify the packages of where your repository classes exist, as shown below:

  @SpringBootApplication
  @ComponentScan("com.ma.demospringboot")
  @EnableJpaRepositories("com.ma.demospringboot.repository")
  @EntityScan(basePackages = "com.ma.demospringboot.domain")
  public class DemoSpringBootApp {
      //your current code here
  }

UPDATE1:

Not a managed type: class com.ma.demospringboot.domain.Topic

Now, your Topic entity class not found, so you need to @EntityScan(basePackages = "com.ma.demospringboot.domain") to scan the entity classes (as show above).

UPDATE2:

I did exactly as you suggested, but NOT working

There is a problem with the way that you are packaging the classes, double check on that, also ensure that the latest classes have been compiled/built & used by the server.

Answer 2

Your Spring container is unable to find and identify your JPA repositories.

Add @EnableJpaRepositories("com.ma.demospringboot.repository") on your DemoSpringBootApp class

@SpringBootApplication
@ComponentScan("com.ma.demospringboot")
@EnableJpaRepositories("com.ma.demospringboot.repository")
public class DemoSpringBootApp {
   public static void main(String[] args) {
      SpringApplication.run(DemoSpringBootApp.class, args);
   }
}

Answer 3

在您的ApplicationContext.xml中添加以下代码

<bean class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />