java - spring-mvc 3.0.5 : what's the preferred way to instantiate the JPA entity manager

Question

我当前的工作代码:

EntityManagerFactory emf = javax.persistence.Persistence.createEntityManagerFactory("TT-SpringMVCPU");
EntityManager em = emf.createEntityManager();

我想用这样的东西替换它:

@PersistenceContext(unitName = "TT-SpringMVCPU")
private EntityManager _entityManager;

当我尝试这样做时，我收到此错误:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'showController': Injection of persistence dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'TT-SpringMVCPU' is defined
    org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor.postProcessPropertyValues(PersistenceAnnotationBeanPostProcessor.java:341)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074)
    org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
...

我忘记配置什么？

Answer 1

来自 Spring 引用手册:Three options for JPA setup in a Spring environment