UnsatisfiedDependencyException：创建名称为bean的错误：通过字段表示的不满意的依赖性

Question

我正在尝试使用Maven按照this教程创建我的第一个Spring MVC Web应用程序，我将用户更改为 Ancestor ，因为我的终极目标是家谱网站。

当我启动我的tomcat服务器时，我遇到以下问题：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'appController': Unsatisfied dependency expressed through field 'ancestorService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.mycompany.service.AncestorService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5118)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5634)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.mycompany.service.AncestorService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1493)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
    ... 24 more

jun 24, 2017 7:59:45 EM org.apache.catalina.core.StandardContext listenerStart
ALLVARLIG: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'appController': Unsatisfied dependency expressed through field 'ancestorService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.mycompany.service.AncestorService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5118)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5634)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.mycompany.service.AncestorService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1493)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:585)
    ... 24 more

jun 24, 2017 7:59:45 EM org.apache.catalina.core.StandardContext listenerStart
ALLVARLIG: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
java.lang.IllegalStateException: Cannot initialize context because there is already a root application context present - check whether you have multiple ContextLoader* definitions in your web.xml!
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:296)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5116)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5634)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1571)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1561)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

我的控制器'AppController'：

@Controller
@RequestMapping("/ancestors")
@SessionAttributes("roles")
public class AppController {

    @Autowired
    AncestorService ancestorService;

    @Autowired
    MessageSource messageSource;

    /**
     * This method will list all existing ancestors.
     */
    @RequestMapping(value = { "/", "/list" }, method = RequestMethod.GET)
    public String listAncestors(ModelMap model) {

        List<Ancestor> ancestors = ancestorService.findAll();
        model.addAttribute("ancestors", ancestors);
        return "ancestorslist";
    }

    /**
     * This method will provide the medium to add a new ancestor.
     */
    @RequestMapping(value = { "/newancestor" }, method = RequestMethod.GET)
    public String newAncestor(ModelMap model) {
        Ancestor ancestor = new Ancestor();
        model.addAttribute("ancestor", ancestor);
        model.addAttribute("edit", false);
        return "registration";
    }

    /**
     * This method will be called on form submission, handling POST request for
     * saving ancestor in database. It also validates the ancestor input
     */
    @RequestMapping(value = { "/newancestor" }, method = RequestMethod.POST)
    public String saveAncestor(@Valid Ancestor ancestor, BindingResult result, ModelMap model) {

        if (result.hasErrors()) {
            return "registration";
        }

        ancestorService.save(ancestor);

        model.addAttribute("success", "Ancestor " + ancestor.getFirst_name() + " "+ ancestor.getLast_name() + " registered successfully");
        return "registrationsuccess";
    }

    /**
     * This method will provide the medium to update an existing ancestor.
     */
    @RequestMapping(value = { "/edit-ancestor-{ssoId}" }, method = RequestMethod.GET)
    public String editAncestor(@PathVariable String ssnId, ModelMap model) {
        Ancestor ancestor = ancestorService.findBySsn(ssnId);
        model.addAttribute("ancestor", ancestor);
        model.addAttribute("edit", true);
        return "registration";
    }

    /**
     * This method will be called on form submission, handling POST request for
     * updating ancestor in database. It also validates the ancestor input
     */
    @RequestMapping(value = { "/edit-ancestor-{ssoId}" }, method = RequestMethod.POST)
    public String updateAncestor(@Valid Ancestor ancestor, BindingResult result,
            ModelMap model, @PathVariable String ssoId) {

        if (result.hasErrors()) {
            return "registration";
        }

        ancestorService.update(ancestor);

        model.addAttribute("success", "Ancestor " + ancestor.getFirst_name() + " "+ ancestor.getLast_name() + " updated successfully");
        return "registrationsuccess";
    }

    /**
     * This method will delete an ancestor by it's SSOID value.
     */
    @RequestMapping(value = { "/delete-ancestor-{ssoId}" }, method = RequestMethod.GET)
    public String deleteAncestor(@PathVariable String ssoId) {
        ancestorService.deleteBySsn(ssoId);
        return "redirect:/list";
    }
}

'AncestorService'：

@Service
public interface AncestorService {

    Ancestor findById(Integer id);

    void save(Ancestor ancestor);

    void update(Ancestor ancestor);

    void deleteBySsn(String ssn);

    List<Ancestor> findAll();

    Ancestor findBySsn(String ssn);

    boolean isSsnUnique(Integer id, String ssn);
}

'AncestorServiceImpl'：

@Service
@Transactional
public class AncestorServiceImpl implements AncestorService {

    @Autowired
    private AncestorDAO dao;

    @Override
    public Ancestor findById(Integer id) {
        return dao.findById(id);
    }

    @Override
    public void save(Ancestor ancestor) {
        save(ancestor);
    }

    @Override
    public void update(Ancestor ancestor) {
        update(ancestor);
    }

    @Override
    public void deleteBySsn(String ssn) {
        dao.deleteBySsn(ssn);
    }

    @Override
    public List<Ancestor> findAll() {
        return dao.findAllAncestors();
    }

    @Override
    public Ancestor findBySsn(String ssn) {
        return dao.findBySsn(ssn);
    }

    @Override
    public boolean isSsnUnique(Integer id, String ssn) {
        Ancestor ancestor = dao.findBySsn(ssn);
        return ( ancestor == null || ((id != null) && (ancestor.getId() == id)));
    }

}

非常感谢任何能够让我了解更多信息甚至帮助我解决问题的输入！