无法自动装配接口

Question

当我尝试从控制器自动连接接口时，出现以下异常： 堆栈跟踪：

Could not autowire field: com.projectShaun.service.AccountService com.projectShaun.controller.HomeController.accountService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'accountService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.projectShaun.dao.AccountDao com.projectShaun.service.AccountServiceImpl.accountDao; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'accountDao': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.hibernate.SessionFactory com.projectShaun.dao.AccountDaoImpl.sessionFactory; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.hibernate.SessionFactory] 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)}

我的控制器如下所示：

package com.projectShaun.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import com.projectShaun.service.AccountService;

@Controller
public class HomeController {

    @Autowired
    AccountService accountService;

    @RequestMapping("/")
    public ModelAndView welcome() {
        ModelAndView modelAndView = new ModelAndView("welcome");
        modelAndView.addObject("greeting", "Welcome to projectShaun!");
        return modelAndView;
    }
}

还有我的应用程序上下文：

<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:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="http://www.springframework.org/schema/aop 
    http://www.springframework.org/schema/aop/spring-aop-3.2.xsd 
    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 
    http://www.springframework.org/schema/jee 
    http://www.springframework.org/schema/jee/spring-jee-3.2.xsd 
    http://www.springframework.org/schema/tx 
    http://www.springframework.org/schema/tx/spring-tx-3.2.xsd 
    http://www.springframework.org/schema/task 
    http://www.springframework.org/schema/task/spring-task-3.2.xsd" >

  <context:component-scan base-package="com.projectShaun.controller" />

  <tx:annotation-driven/>

 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost:3306/projectshaun" />
    <property name="username" value="root" />
    <property name="password" value="" />
  </bean>

  <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource"></property>
     <property name="annotatedClasses">
            <list>
                <value>com.projectShaun.model.Account</value>
            </list>
        </property>
    <property name="hibernateProperties">
      <props>
        <prop 
         key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
        <prop key="hibernate.show_sql">true</prop>
      </props>
    </property>
  </bean>

  <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager" 
    p:sessionFactory-ref="sessionFactory">
  </bean>
</beans>

我不确定它为什么会抛出这个异常，我不确定它是否与上下文有关：组件扫描基础。我试着把com.projectShaun 作为基础包。

AccountDAO：

package com.projectShaun.dao;

import com.projectShaun.model.Account;

public interface AccountDao {

void persistAccount (Account account);
}

Answer 1

异常说：

• 您正确（尝试）在您 HomeController bean 中自动装配 accountService bean
• 您正确地（尝试）在accountService 中自动连接AccountDAO

但错误在于接线AccountDaoImpl.sessionFactory，因为spring 找不到任何org.hibernate.SessionFactory bean。

Answer 2

只有一个spring管理的对象可以Autowire另一个组件/服务/存储库，所以AccountDao需要用@Named或@Component注释为Spring bean。

Answer 3

这里的问题是Spring由于缺少依赖而无法创建Bean

例外是 org.springframework.beans.factory.NoSuchBeanDefinitionException: 否 找到类型为 [org.hibernate.SessionFactory] ​​的合格 bean 依赖项：预计至少有 1 个符合自动装配条件的 bean 这种依赖的候选人。依赖注解： {@org.springframework.beans.factory.annotation.Autowired(required=true)

明确指出它没有为 SessionFactory 配置 bean。 这是 AccountDaoImpl.sessionFactory 所要求的。