Hibernate 4 + Spring：org.springframework.beans.factory.BeanCreationException

Question

我目前正在使用 Hibernate4、Spring 和 JPA 进行一些实现，但我在创建 Bean 时遇到了一些麻烦。

在应用程序中，我们使用一个具有各自配置（C3p0 类、数据源、*hibernate.cfg.xml 和 applicationContext）的 SQL Server 数据库，它可以工作。

但是当我尝试配置另一个数据库 (PostgreSQL) 并使用 JUnit 对其进行测试时，似乎无法创建与 PostgreSQL 数据库的新连接。

但我验证了访问权限，它们在外部 dbview 程序中工作。请考虑以下几点：

堆栈跟踪：

Caused by:
org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'transactionManager' defined in class path resource [config/applicationContext.xml]: 
Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory';
nested exception is org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'sessionFactory' defined in class path resource [config/hibernate.cfg.xml]: Invocation of init method failed;
nested exception is java.lang.NullPointerException

我的hibernate.cfg.xml：

<bean id="dataSourceFactory" class="com.package.myapplication.c3p0"> 
    <constructor-arg type="String" value="${driverClassName}"/>
    <constructor-arg type="String" value="${url}" />
    <constructor-arg type="String" value="${user}" />
    <constructor-arg type="String" value="${password}" />
</bean>
<bean id="dataSource" factory-bean="dataSourceFactory" factory-method="createDriverManagerDataSource"></bean>

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource"></property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">
                          org.hibernate.dialect.PostgreSQLDialect
                    </prop>
            <prop key="hibernate.current_session_context_class">thread</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.c3p0.max_statements">50</prop> 
            <prop key="hibernate.c3p0.max_size">100</prop>
            <prop key="hibernate.c3p0.min_size">5</prop>
        </props>
    </property> 
    <property name="annotatedClasses">
        <list>
              <value>com.package.myapplication.EntityClass</value>
        </list>
    </property>  
</bean>

applicationContext.xml：

<beans>
<context:property-placeholder location="classpath:/database/db.properties" />

 <context:annotation-config />
 <tx:annotation-driven />   

 <bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory" /> 
</bean>  
<import resource="classpath:/config/hibernate.cfg.xml" />
</beans> 

最后我使用以下标头来加载 applicationContext.xml：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="classpath:/config/applicationContext.xml")
@Transactional
public class UnitTest(){
....
}

应用程序是否可能无法处理多个连接（数据源）？还是有其他方法可以使它起作用？

Answer 1

如下更改您的hibernate.cfg.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:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <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="sessionFactory"
      class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
      <property name="dataSource" ref="dataSource" />
      <property name="packagesToScan" value="com.package.myapplication" />
      <property name="hibernateProperties">
       <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.c3p0.max_statements">50</prop> 
            <prop key="hibernate.c3p0.max_size">100</prop>
            <prop key="hibernate.c3p0.min_size">5</prop>
       </props>
  </property>

并确保您是 Hibernate 4 依赖项：

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${springframework.version}</version>
        </dependency>

        <!-- Hibernate -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>4.3.6.Final</version>
        </dependency>