我的目标是从 applicationContext.xml 文件中实例化 EntityManagerFactory 以获取在 SQL 数据库中注册的所有帖子。以下是主要文件的内容：
应用程序上下文.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<!-- Properties files linkers -->
<context:property-placeholder location="/WEB-INF/resources/database/jdbc.properties"/>
<context:property-placeholder location="/WEB-INF/resources/database/hibernate.properties"/>
<!-- Config database - initialization -->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="${jdbc.driverClassName}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</bean>
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
</bean>
<!-- Three main layers definition -->
<context:annotation-config />
<context:component-scan base-package="com.zone42"/>
<!-- Transaction sub-system initialization -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory"/>
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
</beans>
(WEB-INF/classes/)persistence.xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="post-unit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>com.zone42.model.Post</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
</persistence-unit>
</persistence>
PostDAO.java
public class PostDAO extends GenericDAOEntity<Post> implements IPostDAO
{
}
GenericDAOEntity.java
@Transactional
public class GenericDAOEntity<T> implements IGenericDAO<T>
{
/**
* Properties
*/
@Autowired
@PersistenceContext(unitName="post-unit")
private EntityManagerFactory entityManagerFactory/* = Persistence.createEntityManagerFactory(persistence_unit_name)*/;
//Get all posts
@SuppressWarnings("unchecked")
public List<T> findAll(Class<T> obj) {
EntityManager entityManager = this.entityManagerFactory.createEntityManager();
Query query = entityManager.createQuery("from " + obj.getSimpleName());
return (query.getResultList());
}
/**
* Accessors
*/
public EntityManagerFactory getEntityManagerFactory() {
return entityManagerFactory;
}
@PersistenceContext(unitName="post-unit")
public void setEntityManagerFactory(EntityManagerFactory entityManagerFactory) {
this.entityManagerFactory = entityManagerFactory;
}
}
我尝试了几种配置组合，但没有成功。当我想从 entityfactory 实例创建 EntityManager 实例时，来自NullPointerException该方法。findAll我想我有一个配置问题。我想明确代码在我直接在类中使用 operator new 实例化 EntityManagerFactory 时有效。现在我只想分配我的工厂，选择另一种方式，即使用 appicationContext.xml 文件中的 xml。谁能帮我？提前致谢。