我在Spring mvc中遇到错误：
（org.springframework.beans.factory.BeanCreationException：创建名为'webController'的bean时出错：注册自动连接的依赖项失败;嵌套异常是org.springframework.beans.factory.BeanCreationException：无法自动装配字段：private com。 nickolay.app.service.UserService com.nickolay.app.WebController.userService;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：没有找到类型为[com.nickolay.app.service.UserService]的限定bean用于依赖：预计至少有一个bean可以作为此依赖项的autowire候选者。依赖注释）
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'webController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.nickolay.app.service.UserService com.nickolay.app.WebController.userService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.nickolay.app.service.UserService] 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:1214)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:543)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
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:772)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:839)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:538)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:667)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:633)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:681)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:552)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:493)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1231)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1144)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1031)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4997)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5289)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3831)
at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:292)
at org.apache.catalina.core.StandardContext.backgroundProcess(StandardContext.java:5616)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1377)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1381)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1381)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1349)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.nickolay.app.service.UserService com.nickolay.app.WebController.userService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.nickolay.app.service.UserService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:573)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
... 31 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.nickolay.app.service.UserService] 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:1373)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1119)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1014)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:545)
... 33 more
我的控制器（WebController.java）：
@Controller
public class WebController {
@Autowired
private UserService userService;
.................
}
我的UserService.java：
@Service
public class UserService implements UserServiceInterface {
@Autowired
private UserDao userDao;
public void setUserDao(UserDao userDao) {
this.userDao = userDao;
}
@Override
@Transactional
public void create(User user) {
userDao.create(user);
}
................
}
我的HibernateUserDao.java，它实现UserDao：
@Repository("UserDao")
public class HibernateUserDao implements UserDao {
@Autowired
SessionFactory sessionFactory;
public HibernateUserDao() {
}
@Override
@Transactional
public void create(User user) {
if (user == null) {
throw new NullPointerException();
}
Session session = sessionFactory.getCurrentSession();
session.save(user);
}
.............
}
我的servlet-contents.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd"
<annotation-driven />
<tx:annotation-driven />
<resources mapping="/resources/**" location="/resources/" />
<beans:bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<context:component-scan base-package="com.nickolay.app" />
<beans:bean id="userDao" class="com.nickolay.app.dao.HibernateUserDao" />
<beans:bean id="roleDao" class="com.nickolay.app.dao.HibernateRoleDao" />
<beans:bean id="userService" class="com.nickolay.app.service.UserService">
</beans:bean>
</beans:beans>
答案 0 :(得分：1)
在这种情况下，您无法注入具体的类UserService。这是因为Spring正在为您的类创建代理以处理@Transactional。由于您的服务实现了一个接口，Spring正在创建一个基于JDK接口的代理，即代理实现UserServiceInterface并委托给UserService。因此，Spring管理的bean不是UserService而是UserServiceInterface
有两种方法可以解决这个问题。最简单的方法是将依赖项从UserService更改为UserServiceInterface
@Controller
public class WebController {
@Autowired
private UserServiceInterface userService;
}
第二种方法是指示Spring使用基于CGLIB类的代理而不是基于JDK接口的代理。更改tx：annotation-driven以将proxy-target-class指定为true
<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:beans="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.2.xsd"
<annotation-driven />
<tx:annotation-driven proxy-target-class="true/>
<resources mapping="/resources/**" location="/resources/" />
<beans:bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<beans:property name="prefix" value="/WEB-INF/views/" />
<beans:property name="suffix" value=".jsp" />
</beans:bean>
<context:component-scan base-package="com.nickolay.app" />
<beans:bean id="userDao" class="com.nickolay.app.dao.HibernateUserDao" />
<beans:bean id="roleDao" class="com.nickolay.app.dao.HibernateRoleDao" />
<beans:bean id="userService" class="com.nickolay.app.service.UserService">
</beans:bean>
</beans:beans>