春天不能自动接线。为什么？ [英] Could not autowire field in spring. why?

问题描述

我不断得到这个错误，不知道为什么..是的，我知道有很多人有类似的问题，但阅读他们得到的答案，并没有解决我的问题。

I keep getting this error, and can't figure out why.. yes I know there many people had similar issues, but reading the answers they got, does not solve my problem.

org.springframework.beans.factory.BeanCreationException：创建名为'contactController'的bean时出错：自动连线依赖关系的注入失败;嵌套异常是org.springframework.beans.factory.BeanCreationException：无法自动连线字段：private net.service.ContactService net.controller.ContactController.contactService;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：找不到依赖关系类型为[net.service.ContactService]的匹配bean：至少有1个bean被认定为此依赖关系的自动连线候选。依赖关系注释：{@ org.springframework.beans.factory.annotation.Autowired（required = true）}

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'contactController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private net.service.ContactService net.controller.ContactController.contactService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [net.service.ContactService] 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)}

这里是控制器：

@Controller
@SessionAttributes
public class ContactController {

    @Autowired
    private ContactService contactService;
//methods...


}

ContactServiceImpl

@Service("contactService")
@Transactional(propagation = Propagation.SUPPORTS, readOnly = true)
public class ContactServiceImpl implements ContactService {

    @Autowired
    private ContactDao contactDao;

    public ContactServiceImpl() {
    }

    @Override
    @Transactional(propagation = Propagation.REQUIRED, readOnly = false)
    public void addContact(Contact contact) {
        contactDao.saveContact(contact);
    }

    @Override
    public List<Contact> getContacts() {
        return contactDao.getAllContacts();
    }

}

ContactDaoImpl

the ContactDaoImpl

@Repository("contactDao")
public class ContactDaoImpl implements ContactDao {

    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public void saveContact(Contact contact) {
        sessionFactory.getCurrentSession().saveOrUpdate(contact);
    }

    @Override
    @SuppressWarnings("unchecked")
    public List<Contact> getAllContacts() {
        return (List<Contact>) sessionFactory.getCurrentSession().createQuery("from contact c").list();
    }

}

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:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

    <context:property-placeholder location="classpath:jdbc.properties" />
    <context:component-scan base-package="net.controller" />


    <tx:annotation-driven transaction-manager="hibernateTransactionManager" />

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

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${database.driver}" />
        <property name="url" value="${database.url}" />
        <property name="username" value="${database.user}" />
        <property name="password" value="${database.password}" />
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="annotatedClasses">
            <list>
                <value>net.form.Contact</value>
            </list>
        </property>


        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
            </props>
        </property>
    </bean>

    <bean id="hibernateTransactionManager"
        class="org.springframework.orm.hibernate3.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>
</beans>

推荐答案

在spring servlet中.xml：

In spring servlet .xml :

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

（我假设服务impl与服务接口net.service在同一个包中）

(I assumed that the service impl is in the same package as the service interface "net.service")

我认为您必须将net.service包（或全部网络）添加到组件扫描中。目前，spring只在net.controller中搜索组件，并且您的服务impl在net.service中，它将不会在春天实例化。

I think you have to add the package net.service (or all of net) to the component scan. Currently spring only searches in net.controller for components and as your service impl is in net.service, it will not be instantiated by spring.

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