spring - 无法 Autowiring 字段

Question

我正在使用Hibernate 4 + Spring MVC 4当我开始 Apache Tomcat Server 8我收到此错误:

Error creating bean with name 'welcome': Injection of autowired dependencies failed;
Could not autowire field: private dao.IRegion controller.welcome.regionI;
No qualifying bean of type [dao.IRegion] 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)}

这是我的 Hibernate 配置，其中包含 <property name="packagesToScan" value="dao" /> :

<?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"
   xsi:schemaLocation="
      http://www.springframework.org/schema/beans 
      http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
      http://www.springframework.org/schema/context 
      http://www.springframework.org/schema/context/spring-context-3.2.xsd">

   <context:property-placeholder location="persistence-mysql.properties" />

   <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <property name="packagesToScan" value="dao" />
      <property name="hibernateProperties">
         <props>
            <prop key="hibernate.dialect">${hibernate.dialect}</prop>
         </props>
      </property>
   </bean>

<!--    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> -->
   <bean id="dataSource" class="org.apache.tomcat.dbcp.dbcp2.BasicDataSource">
      <property name="driverClassName" value="${jdbc.driverClassName}" />
      <property name="url" value="${jdbc.url}" />
      <property name="username" value="${jdbc.user}" />
      <property name="password" value="${jdbc.pass}" />
   </bean>

   <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
      <property name="sessionFactory" ref="sessionFactory" />
   </bean>

   <bean id="persistenceExceptionTranslationPostProcessor" class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor"/>

</beans>

dao 是我放置 dao 和接口(interface)的包。

我的区域界面dao.IRegion :

public interface IRegion<T extends Serializable> {

    List<T> findAll();

}

我的区域 DAO dao.RegionDAO

@Repository
public class RegionDAO  implements IRegion < Region > {

    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public List<Region> findAll() {

        return  sessionFactory.getCurrentSession().createQuery("from Region").list();
    }

}

我的 Controller

@Controller
public class welcome {

    @Autowired
    private IRegion<Region> regionI;
        ....

}

我的 servlet 调度程序

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
                           http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/mvc
                           http://www.springframework.org/schema/mvc/spring-mvc.xsd
                           http://www.springframework.org/schema/context
                           http://www.springframework.org/schema/context/spring-context.xsd">
    <mvc:default-servlet-handler />
    <context:component-scan base-package="controller"/>
    <mvc:annotation-driven />

    <mvc:resources mapping="/resources/**" location="/resources/" />  

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


</beans>

Answer 1

RegionDao 类型的 bean 永远不会由 Spring IOC 容器创建，因此该 bean 不受 Spring 管理，这使得它无法进行 Autowiring 。 Spring 基本上是说，我在 Controller 中没有任何满足此依赖关系的 bean。

为了让 RegionDao 由 Spring 创建和管理，组件会扫描 hibernate 配置文件中类的包。

<context:component-scan base-package="package.with.daos"/>

这将在 Spring IOC 容器内创建一个 RegionDao 类型的 bean，并使其可用于 Autowiring 。