java - 在Spring中使用@Autowired注解时出现以下错误，该如何解决？

Question

我是 Spring 新手，在尝试使用 @Autowired 注释、尝试将 Repository 类注入(inject) PostController 时遇到一些问题

@Controller
@RequestMapping("/posts")

public class PostController {


    @Autowired 
    private Repository repository;


    @RequestMapping(value="",method= RequestMethod.GET)
    public String listPosts(Model model){
        model.addAttribute("posts",repository.findAll());
        return "posts/lists";
    }
}

public interface Repository extends CrudRepository<Posts,Long> {
}

这些是我收到的错误消息

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'postController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private domain.Repository controllers.PostController.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [domain.Repository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1208) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:759) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480) at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:117) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:689) at org.springframework.boot.SpringApplication.run(SpringApplication.java:321) at org.springframework.boot.SpringApplication.run(SpringApplication.java:969) at org.springframework.boot.SpringApplication.run(SpringApplication.java:958) at MyApplication.main(MyApplication.java:7) Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private domain.Repository controllers.PostController.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [domain.Repository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331) ... 16 more Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [domain.Repository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1301) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1047) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533) ... 18 more

Answer 1

您必须创建自己的存储库并从存储库扩展它，现在您正在使用 spring Repository 接口(interface)。

@Repository
public interface PostRepository extends CrudRepository<Posts,Long> {

}

和@Autowire它

@Autowired 
private PostRepository repository;