NoUniqueBeanDefinitionException：没有定义类型的限定 bean：预期的单个匹配 bean 但找到了 2

【问题标题】：NoUniqueBeanDefinitionException: No qualifying bean of type is defined: expected single matching bean but found 2NoUniqueBeanDefinitionException：没有定义类型的限定 bean：预期的单个匹配 bean 但找到了 2
【发布时间】：2013-10-17 19:03:36
【问题描述】：

当我尝试使用 Springs MVC 配置我的 GAE Web 项目时，我遇到了以下异常。我在我的文件中使用了以下配置。我正在使用 Springs 的 spring-3.2.3 版本，并且我的类路径中已经有 spring-bean-3.2.3.jar。

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd">

    <context:annotation-config />

    <context:component-scan base-package="com.myweb.webservices" />

    <bean id="cnManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
        <property name="favorPathExtension" value="true"/>
        <property name="ignoreAcceptHeader" value="true" />
        <property name="defaultContentType" value="text/html" />
        <property name="useJaf" value="false"/>

        <property name="mediaTypes">
            <map>
                <entry key="html" value="text/html" />
                <entry key="json" value="application/json" />
                <entry key="xml" value="application/xml" />
            </map>
        </property>
    </bean>

    <mvc:annotation-driven/>
    <mvc:annotation-driven content-negotiation-manager="cnManager"/>

    <bean class="com.myweb.webservices.spring.MvcConfiguringPostProcessor" />
</beans>

spring-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-3.2.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.2.xsd">


    <context:annotation-config />
    <context:component-scan base-package="com.myweb.webservices."/>
    <context:component-scan base-package="com.myweb.webservices.dao"/>
    <context:component-scan base-package="com.myweb.webservices.service"/>
    <context:component-scan base-package="com.myweb.webservices.controller"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" 
      p:prefix="/jsp/" p:suffix=".jsp" />
</beans>

GenericDao.java

public interface GenericDao {
    public <T> void create(T t);
}

AbstractGenericDaoImpl.java

public abstract class AbstractGenericDaoImpl implements GenericDao{

    static {
        ObjectifyService.register(User.class);
    }

    @Override
    public <T> void create(T t) {
        ofy().save().entity(t).now();
    }
}

GenericService.java

public interface GenericService {
    public <T> void create(T t);
}

AbstractGenericServiceImpl.java

public abstract class AbstractGenericServiceImpl implements GenericService{

    @Autowired
    GenericDao genericDao;

    @Override
    public <T> void create(T t) {
        genericDao.create(t);
    }
}

例外

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.security.filterChains': Cannot resolve reference to bean 'org.springframework.security.web.DefaultSecurityFilterChain#0' while setting bean property 'sourceList' with key [0]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.security.web.DefaultSecurityFilterChain#0': Cannot resolve reference to bean 'authenticationFilter' while setting constructor argument with key [2]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'authenticationFilter' defined in ServletContext resource [/WEB-INF/spring-security.xml]: Cannot resolve reference to bean 'customAuthenticationManager' while setting bean property 'authenticationManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'customAuthenticationManager': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.myweb.webservices.service.UserService com.myweb.webservices.authentication.CustomAuthenticationManager.userService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.myweb.webservices.common.dao.GenericDao com.myweb.webservices.common.dao.AbstractGenericServiceImpl.genericDao; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.myweb.webservices.common.dao.GenericDao] is defined: expected single matching bean but found 2: testDao,userDao
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:329)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:107)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:353)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:154)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1387)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1128)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:608)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:548)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:136)
at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:130)
at org.mortbay.jetty.Server.doStart(Server.java:224)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
at com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerService.java:249)
at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:307)
at com.google.appengine.tools.development.AutomaticServerInstanceHolder.startUp(AutomaticServerInstanceHolder.java:26)
at com.google.appengine.tools.development.AbstractServer.startup(AbstractServer.java:80)
at com.google.appengine.tools.development.Servers.startup(Servers.java:82)
at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:237)
at com.google.appengine.tools.development.DevAppServerMain$StartAction.apply(DevAppServerMain.java:339)
at com.google.appengine.tools.util.Parser$ParseResult.applyArgs(Parser.java:48)
at com.google.appengine.tools.development.DevAppServerMain.<init>(DevAppServerMain.java:274)
at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:250)

【问题讨论】：

    标签： spring-mvc spring-security beancreationexception


    【解决方案1】：

    错误是

    No qualifying bean of type [com.myweb.webservices.common.dao.GenericDao] is defined: expected single matching bean but found 2: testDao,userDao

    在组件扫描的某个包中的某处，您正在创建UserDao 和TestDao。由于它们都是GenericDao 的实现，因此它们会发生冲突，因为它们将用作@Autowired 目标。我相信你应该在这种情况下摆脱你的TestDao。

    没有看到你的其余配置，这在你的根上下文中

    <context:component-scan base-package="com.myweb.webservices" />

    以及在 servlet 上下文中的 this

    <context:component-scan base-package="com.myweb.webservices."/>
<context:component-scan base-package="com.myweb.webservices.dao"/>
<context:component-scan base-package="com.myweb.webservices.service"/>
<context:component-scan base-package="com.myweb.webservices.controller"/>

    将创建重复的 bean，这很可能会导致更多问题。使您的组件扫描尽可能具体。组件扫描是通过包递归的。

    这个豆子

    <bean id="cnManager" class="org.springframework.web.accept.ContentNegotiationManagerFactoryBean">
...

    仅与您的 servlet 相关。它应该在 servlet 上下文中，而不是根上下文中。

    在您的 servlet 上下文中，不要忘记启用 

    <mvc:annotation-driven />

    【讨论】：

    • 先生，我有一个 GenericDao，GenricService 及其实现，它们由 UserDao，TestDao 实现。我需要制作一个通用模型，以便后者可以使用通用接口和类中的方法。
    • @ankur 您的AbstractGenericServiceImpl 课程中的这个@Autowired GenericDao genericDao; 将不起作用，因为Spring 为它找到了两个候选人并且无法选择哪一个。重新考虑您的设计或使用 @Qualified 注释具体指定哪个 bean。
    • 先生，我已经从 GenericDao 中删除了 @Autowired 并且异常消失了。但是你能指导我如何在不使用 @Autowired 注释的情况下使用服务层访问 DAO 层。
    • @AnkurJain 您应该通过指定特定类型在您的@Service 类中使用@Autowired。如果您需要UserDao，请自动连接UserDao，而不是GenericDao。
    • 先生，我已经在我的 UserDaoImpl 中使用了@Repository，在 UserServiceImpl 中使用了@Service，但这对我也不起作用。此外，我需要有一个通用模板服务和 DAO 层，我可以在进一步的实体 DAO 和服务中实现。
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