spring - 字段 Autowiring 失败异常

Question

我正在使用 Spring MVC Portlet，但遇到了问题。我的应用程序在它有一个 bean 时工作正常。如果我想在下面添加另一个 bean，则会发生错误。

错误日志在这里；

ERROR [org.springframework.web.portlet.DispatcherPortlet] - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'addSinifController': Autowiring of fields failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.project.service.SinifService com.project.controller.AddSinifController.sinifService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mySinifService' defined in file [/tmp/1-sample_BookCatalog/WEB-INF/classes/com/project/service/SinifService.class]: Instantiation of bean failed; nested exception is java.lang.ExceptionInInitializerError
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessAfterInstantiation(AutowiredAnnotationBeanPostProcessor.java:280)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1011)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:511)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:450)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:289)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:286)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:188)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:543)
    at 
...

我的 application-context.xml ；

<context:annotation-config/>

<context:component-scan base-package="sample.code.listing" />
<context:component-scan base-package="com.project.controller" />
<context:component-scan base-package="com.project.domain" />
<context:component-scan base-package="com.project.service" />

<bean
    class="org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="webBindingInitializer">
        <bean
            class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer">
            <property name="propertyEditorRegistrars">
                <list>
                    <ref bean="myPropertyEditorRegistrar" />
                </list>
            </property>
        </bean>
    </property>
</bean>

<bean id="myPropertyEditorRegistrar" class="sample.code.listing.utils.MyPropertyEditorRegistrar"/>

<bean id="messageSource"
    class="org.springframework.context.support.ResourceBundleMessageSource">
    <property name="basenames">
        <list>
            <value>content.Language-ext</value>
        </list>
    </property>
</bean>

<bean id="viewResolver"
    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="viewClass"
        value="org.springframework.web.servlet.view.JstlView" />
    <property name="prefix" value="/WEB-INF/jsp/" />
    <property name="suffix" value=".jsp" />
</bean>

我的 AddSinifController 在这里:

@Controller(value="addSinifController")
@RequestMapping(value="VIEW")
@SessionAttributes(types=Sinif.class)
public class AddSinifController {

    @Autowired
    @Qualifier("mySinifService")
    private SinifService sinifService;

    public SinifService getSinifService() {
        return sinifService;
    }

    public void setSinifService(SinifService sinifService) {
        this.sinifService = sinifService;
    }

    private Logger logger = Logger.getLogger(AddSinifController.class);

    @RenderMapping(params = "myaction=addsinif")
    public String showAddSinifForm(RenderResponse response,ModelMap model){
        return "addSinifForm";
    }

    @RenderMapping(params = "myaction=home")
    public String showhome(RenderResponse response,ModelMap model) {    
        return "home";      
    }

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        binder.registerCustomEditor(Long.class, new LongNumberEditor());

    }
    @ModelAttribute("sinif")
    public Sinif getCommandObject(){
        return new Sinif("sinif");
    }
    @ModelAttribute(value = "myaction=siniflar")
    public List<Sinif> getCommandObject2(){
        return sinifService.getSiniflar();
    }
    @ActionMapping(params="myaction=addSinif")
    public void addSinif(@ModelAttribute Sinif sinif,
            BindingResult bindingResult, ActionResponse response,
            SessionStatus sessionStatus){
            Kademe kademe = new Kademe("kademe");
            kademe.setId((long) 6);
            sinif.setKademe(kademe);
 }          
            sinifService.addSinif(sinif);
            response.setRenderParameter("myaction", "addsinif");
            sessionStatus.setComplete();

        if(!bindingResult.hasErrors()){
            System.out.println("hata yok");
            sinifService.addSinif(sinif);
            response.setRenderParameter("myaction", "addsinif");
            sessionStatus.setComplete();
        }else{
            response.setRenderParameter("myaction", "home");
        }
    }


}

问候

Answer 1

给出相同的注释

@Qualifier("mySinifService")

到实现您要实例化的 SinifService 接口(interface)的类。基本上，这里的问题是，当您要求 Spring 在 AddSinifController 类中 Autowiring SinifService 接口(interface)时，当您有多个实现您的接口(interface)的类时，Spring 不知道要实例化接口(interface)的哪个实现。通过提供 @Qualifier 注释，您指的是要实例化的特定 bean。