利用Spring的事务管理无法将数据写到数据库中啊
下面是我的代码：
applicationContext.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"
    default-autowire="byName" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

	<!-- 自动扫描的包名 -->
	<context:component-scan base-package="com.github.Yasenia.flea_school.server">
	</context:component-scan>

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

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

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

	<bean id="jpaDialect" 
		class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/> 
</beans>

springMVC-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" default-autowire="byName"
	xmlns:mvc="http://www.springframework.org/schema/mvc"
	xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

	<!-- 自动扫描的包名 -->
	<context:component-scan base-package="com.github.Yasenia.flea_school.server">
	</context:component-scan>

	<!-- 默认的注解映射的支持 -->
	<mvc:annotation-driven />

	<!-- 视图解释类 -->
	<bean
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/jsp/" />
		<property name="suffix" value=".jsp" />
	</bean>


	<!-- 对静态资源文件的访问 方案 -->
	<mvc:default-servlet-handler />
</beans>

IUserDAOImpl.java

@Named
public class UserDAOImpl implements IUserDAO {

    @PersistenceContext
    private EntityManager em;

    public void save(User user) {
        em.persist(user);
    }
    ...
}

IUserService.java:

@Named
public class UserServiceImpl implements IUserService {
    @Inject
    private IUserDAO userDAO;
    

    @Transactional(propagation = Propagation.REQUIRED)
    public void save(User user) {
        user.setRegisterDate(new Date());
        userDAO.save(user);
    }
}

我手动开启和提交事务也不行

    public void save(User user) {
        System.out.println("userDAO working");
        EntityTransaction transaction = em.getTransaction(); 
        transaction.begin();
        System.out.println("userDAO saving");
        System.out.println("em is: " + em);
        em.persist(user);
        transaction.commit();

    }

执行到EntityTransaction transaction = em.getTransaction();这句话就会退出方法。

不知道是什么原因，求大神指点啊！