@Autowired entityManagerFactory为空 [英] @Autowired entityManagerFactory is null

问题描述

我的应用无法自动连接entityManagerFactory.

我的 applicationContext.xml :

 < tx:注解驱动/>< context:component-scan base-package ="top.level.package"/>< bean id ="persistenceUnitManager"class ="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager"><属性名称="persistenceXmlLocation">< value> classpath:jpa-persistence.xml</value></property></bean>< bean id ="entityManagerFactory"class ="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"><属性名称="persistenceUnitManager" ref ="persistenceUnitManager"/></bean>< bean id ="transactionManager"class ="org.springframework.orm.jpa.JpaTransactionManager"><属性名称="entityManagerFactory" ref ="entityManagerFactory"/></bean> 

我的 java类:

  @Component公共类引擎{@Autowired@Qualifier("entityManagerFactory")私有EntityManagerFactory实体管理器工厂；......} 

问题:

为什么entityManagerFactory为空?

解决方案

要让spring使用注释进行自动扭曲，您必须告诉spring.在您的xml配置中(假设您还没有 context:component-scan 元素)，添加一个 context:annotation-config .这将指示Spring应用程序上下文扫描注释(例如 @Autowired ， @Inject ， @Resource 等)以进行自动装配./p>

还要确保要将 EntityManagerFactory 注入到的类( Engine 类)是spring托管bean.Spring只会将引用注入到Spring托管的bean中.

My app can't autowire entityManagerFactory.

My applicationContext.xml:

<tx:annotation-driven/>
<context:component-scan base-package="top.level.package" />

<bean id="persistenceUnitManager"     
    class="org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager">
    <property name="persistenceXmlLocation">
        <value>classpath:jpa-persistence.xml</value>
    </property>
</bean>

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

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

My java class:

@Component
public class Engine {

    @Autowired
    @Qualifier("entityManagerFactory")
    private EntityManagerFactory entityManagerFactory;
......
}

Question:

Why entityManagerFactory is null?

解决方案

For spring to do autowring using annotations you have to tell spring that. In your xml configuration (assuming you don't already have context:component-scan element) add a context:annotation-config. This will instruct the spring application context to scan for annotations (like @Autowired, @Inject, @Resource etc.) to do autowiring.

Also make sure that the class you want the EntityManagerFactory to be injected into (the Engine class) is a spring managed bean. Spring will only inject references into spring managed beans.

这篇关于@Autowired entityManagerFactory为空的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！