Question

我对spring和java很新。我一直在使用springsource.org来尝试通过创建spring 3 MVC Web应用程序来工作。我让它工作，我可以获取信息并与控制器和管理器一起显示。

现在我正在研究编辑信息并将其保存回数据库的功能。我在我的服务类中的保存功能中添加了@Transactional注释，现在我收到了UnsatisfiedDependencyException。作为一个非常新的，我不知道该怎么做才能清除它。我为我的EventsManager添加了一个bean，但我认为没有必要，因为Annotations假设不再需要大量的xml配置文件。我不确定错误在哪里，所以我发布了我的源代码。感谢您抽出宝贵时间帮我解决问题。

完全例外：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'eventsController' defined in file [$Path\gov\mt\dphhs\epts\web\EventsController.class]: Unsatisfied dependency expressed through constructor argument with index 0 of type [gov.mt.dphhs.epts.services.EventsManager]: : No matching bean of type [gov.mt.dphhs.epts.services.EventsManager] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [gov.mt.dphhs.epts.services.EventsManager] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}

控制器类：

@Controller
public class EventsController {

    private EventsManager eventsManager;

    @Autowired
    public EventsController(EventsManager eventsManager){
        this.eventsManager = eventsManager;
    }

    @RequestMapping("/events/events")
    public String displayEvents(ModelMap map){

        map.addAttribute("allEvents", eventsManager.getAllEvents());

        int totalEvents = eventsManager.getAllEvents().size();
        map.addAttribute("totalEvents",totalEvents);

        map.addAttribute("eventsTitle" , totalEvents + " Events");

        return "events";
    }

    @RequestMapping("/events/eventForm")
    public String editEvents(@RequestParam("id") Long eventId, ModelMap map){

        Events event = eventsManager.getEventById(eventId);
        map.addAttribute("pageTitle" , "Edit Event");
        map.addAttribute("event",event);

        return "eventForm";
    }

    @RequestMapping("/events/newEvent")
    public String newEvent(ModelMap map){

        Events event = new Events();
        map.addAttribute("pageTitle" , "New Event");
        map.addAttribute("event",event);

        return "eventForm";
    }

    @RequestMapping("/events/submitEvent")
    public String handleEventForm(@ModelAttribute("event")
            Events event, BindingResult result){

        System.out.println("Event Name:" + event.getEventName() + " ID: " + event.getEvntId());

        if(event.getEvntId() == null)
        {
            eventsManager.save(event);
        }

        return "redirect:/events/events";
    }   
}

服务类：

@Service("EventsManager")
public class EventsManager implements IEventsManager {


    private EventsDAO eventsDao;

    @Autowired
    public void EventsDAO(EventsDAO eventsDao) {
        this.eventsDao = eventsDao;
    }

    public List<Events> getAllEvents() {
        return eventsDao.findAll();
    }

    public Events getEventById(Long id) {

        return eventsDao.findById(id);
    }

    public void delete(Events event) {
        // TODO Auto-generated method stub

    }

    @Transactional
    public void save(Events event) {
        eventsDao.save(event);
    }

    public Events update(Events event) {

        return eventsDao.update(event);
    }

}

修剪了我的Dao课程版本：

public class EventsDAO implements IEventsDAO {

    @PersistenceContext
    private EntityManager em;

    protected final Log logger = LogFactory.getLog(EventsDAO.class);

    public void save(Events entity) {
        System.out.println("in Dao to save an event");
        logger.info("saving Events instance");
        try {
            em.persist(entity);
            logger.info("save successful");
        } catch (RuntimeException re) {
            logger.error("save failed", re);
            throw re;
        }
    }

    public EntityManager getEm() {
        return em;
    }

    public void setEm(EntityManager em) {
        this.em = em;
    }

    public static IEventsDAO getFromApplicationContext(ApplicationContext ctx) {
        return (IEventsDAO) ctx.getBean("EventsDAO");
    }
}

应用程序上下文：

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

<context:component-scan base-package="gov.mt.dphhs.epts" />

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

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
    <property name="persistenceUnitName" value="EPTSTest3Pu" />
</bean>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

<tx:annotation-driven transaction-manager="transactionManager" />
<context:annotation-config />

<bean id="EventsManager" class="gov.mt.dphhs.epts.services.EventsManager" />

<bean id="SpecialGuestsDAO" class="gov.mt.dphhs.epts.repository.SpecialGuestsDAO" />

<bean id="GroupMembersDAO" class="gov.mt.dphhs.epts.repository.GroupMembersDAO" />

<bean id="GroupsDAO" class="gov.mt.dphhs.epts.repository.GroupsDAO" />

<bean id="EventNotificationsDAO" class="gov.mt.dphhs.epts.repository.EventNotificationsDAO" />

<bean id="EventListingsDAO" class="gov.mt.dphhs.epts.repository.EventListingsDAO" />

<bean id="EventGroupXrefDAO" class="gov.mt.dphhs.epts.repository.EventGroupXrefDAO" />

<bean id="EventsDAO" class="gov.mt.dphhs.epts.repository.EventsDAO" />

Answer 1

看起来autowire注释感到困惑，但我无法确定。

您在EventsController中声明的依赖关系是对具体EventsManager类的依赖，而不是IEventsManager接口，这是更好的做法，即代码到接口。 Spring使用一些智能来自动连接bean，例如按类型自动装配和按名称自动装配。例如（我正在简化）spring将检查bean容器中是否匹配的类型或匹配的名称。我会假设按类型自动装配使用具体类型，但可能会有一些特性在这里解雇。

我建议：

在你的中使用IEventsManager 控制器，并说明该类型构造函数参数中的依赖项
用小写的首字母命名你的spring bean，就像你的java字段/变量命名约定（然后spring可以按名称自动连接，将“eventsManager”构造函数参数匹配到“eventsManager”spring bean）

此外，看起来你要两次指定一些豆子。使用@Service注释并对该包执行组件扫描时，无需在上下文文件中再次指定它。所以你的“EventsManager”bean已经定义了两次，但我不确定这是否会导致你的依赖性问题。

Spring 3 MVC：@Transactional添加到Service类，现在变得异常

1 个答案: