将Bean类与RestController自动连接时发生java错误

Question

DAO接口

@Repository
public interface UserDAO {
    // some methods...
}

DAO实现类（使用@Repository注释）

@Repository("userDAO")
public class UserDAOImpl {
    // some implementation code.
}

服务接口

@Service
public interface UserService {
    // some methods...
}

服务类（使用@Service注释）

@Service("userService")
public class UserServiceImpl {
    // implementation o service method...
}

RestController（使用@Autowired注释）

@RestController
@RequestMapping("/api")
@CrossOrigin(origins="http://localhost:4200" , allowedHeaders="*")
public class UserRestController {
    //  Autowired the Service class
    @Autowired
    @Qualifier("userService")
    private UserService userService;
    // implementation code...
}

在所有这些步骤之后，我仍然得到以下异常

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.javatpoint.LoginLogoutRest.service.TokenService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=tokenService)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1509)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    ... 30 more

    Jul 20, 2018 5:12:06 PM org.apache.catalina.core.ApplicationContext log
    SEVERE: StandardWrapper.Throwable
    org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userLoginRestController': Unsatisfied dependency expressed through field 'tokenService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.javatpoint.LoginLogoutRest.service.TokenService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=tokenService)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:587)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:91)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:373)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1348)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:578)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:501)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:760)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:672)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:541)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:499)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:172)
    at javax.servlet.GenericServlet.init(GenericServlet.java:158)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1174)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:983)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4829)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5139)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3700)
    at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:292)
    at org.apache.catalina.core.StandardContext.backgroundProcess(StandardContext.java:5461)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1394)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1398)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1398)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1366)
    at java.lang.Thread.run(Unknown Source)
    Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.javatpoint.LoginLogoutRest.service.TokenService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=tokenService)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1509)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1065)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:584)
    ... 30 more

我正在做这个没有XML的项目

请帮我解决这个问题

Answer 1

我忘了实现接口。这就是问题所在

在DAO实现类中，它应该是

public class UserDAOImpl implements UserDAO {  }

在服务课上应该是这样的

public class UserServiceImpl implements UserService {  }

Answer 2

无需在接口内放置@service注释

例如DAO接口和服务接口

  public interface UserDAO {
    // some methods...
    }

//Service
public interface UserService {
  // some methods...
}