使用 Spring 依赖注入时，Hibernate SessionFactory 始终为 null
The Hibernate SessionFactory is always null when using Spring dependency injection
我在 CityDaoImpl 中的保存方法中收到 NullpointerException。似乎 sessionFactory 没有自动装配，因为在调试时发现 sessionFactory 从未注入 CityDaoImpl。我浏览了很多答案，但其中 none 可以解决我的问题。
这是我的 HibernateConfig.xml 文件：
<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"
xsi:schemaLocation=
"http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan
base-package="com.testing" />
<context:annotation-config></context:annotation-config>
<tx:annotation-driven/>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/sybrium" />
<property name="username" value="root" />
<property name="password" value="" />
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref="dataSource"></property>
<property name="annotatedClasses">
<list>
<value>com.testing.bean.City</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">create</prop>
<prop key="debug">true</prop>
</props>
</property>
</bean>
<bean id="cityDao" class="com.testing.dao.CityDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
</beans>
这是 CityDaoImpl.java :
public class CityDaoImpl implements CityDao{
@Autowired
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sessionFactory){
this.sessionFactory = sessionFactory;
}
public void save(City city){
this.sessionFactory.getCurrentSession().save(city);
}
}
现在我正在对我的 dao class 执行单元测试。但因 NPE 而失败。
public class TestCityDao {
ApplicationContext ctx;
@Before
public void setup(){
ctx = new ClassPathXmlApplicationContext("HibernateConfig.xml");
}
@Test
public void test(){
City city = new City();
city.setName("Karachi");
city.setCountry("Pakistan");
CityDao dao = (CityDao) ctx.getBean("cityDao");
dao.save(city);
}
}
控制台输出：
Jan 15, 2015 11:54:53 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3: display name [org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3]; startup date [Thu Jan 15 23:54:53 PKT 2015]; root of context hierarchy
Jan 15, 2015 11:54:53 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [HibernateConfig.xml]
Jan 15, 2015 11:54:53 PM org.springframework.context.support.AbstractApplicationContext obtainFreshBeanFactory
INFO: Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3]: org.springframework.beans.factory.support.DefaultListableBeanFactory@1b8202e
Jan 15, 2015 11:54:53 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1b8202e: defining beans [dataSource,sessionFactory,cityDao]; root of factory hierarchy
Jan 15, 2015 11:54:53 PM org.springframework.jdbc.datasource.DriverManagerDataSource setDriverClassName
INFO: Loaded JDBC driver: com.mysql.jdbc.Driver
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Jan 15, 2015 11:54:53 PM org.springframework.orm.hibernate3.LocalSessionFactoryBean buildSessionFactory
INFO: Building new Hibernate SessionFactory
抛出的异常是：
java.lang.NullPointerException
at com.testing.dao.CityDaoImpl.save(CityDaoImpl.java:19)
at com.testing.TestCityDao.test(TestCityDao.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access[=15=]0(ParentRunner.java:53)
at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
您声明了 sessionFactory 依赖项：
<bean id="cityDao" class="com.testing.dao.CityDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
然后你还有：
@Autowired
private SessionFactory sessionFactory;
尝试删除 @Autowired 注释，因为如果您使用 XML 配置，它是多余的。
仅仅因为你添加了sessionFactory，并不意味着Spring也可以自动管理Hibernate Sessions。
您还需要添加：
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
以及：
<tx:annotation-driven/>
现在您还需要将 @Transactional 添加到您的 save 例程中：
@Transactional
public void save(City city){
this.sessionFactory.getCurrentSession().save(city);
}
我在 CityDaoImpl 中的保存方法中收到 NullpointerException。似乎 sessionFactory 没有自动装配，因为在调试时发现 sessionFactory 从未注入 CityDaoImpl。我浏览了很多答案，但其中 none 可以解决我的问题。
这是我的 HibernateConfig.xml 文件：
<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"
xsi:schemaLocation=
"http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan
base-package="com.testing" />
<context:annotation-config></context:annotation-config>
<tx:annotation-driven/>
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/sybrium" />
<property name="username" value="root" />
<property name="password" value="" />
</bean>
<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
<property name="dataSource" ref="dataSource"></property>
<property name="annotatedClasses">
<list>
<value>com.testing.bean.City</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.hbm2ddl.auto">create</prop>
<prop key="debug">true</prop>
</props>
</property>
</bean>
<bean id="cityDao" class="com.testing.dao.CityDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
</beans>
这是 CityDaoImpl.java :
public class CityDaoImpl implements CityDao{
@Autowired
private SessionFactory sessionFactory;
public void setSessionFactory(SessionFactory sessionFactory){
this.sessionFactory = sessionFactory;
}
public void save(City city){
this.sessionFactory.getCurrentSession().save(city);
}
}
现在我正在对我的 dao class 执行单元测试。但因 NPE 而失败。
public class TestCityDao {
ApplicationContext ctx;
@Before
public void setup(){
ctx = new ClassPathXmlApplicationContext("HibernateConfig.xml");
}
@Test
public void test(){
City city = new City();
city.setName("Karachi");
city.setCountry("Pakistan");
CityDao dao = (CityDao) ctx.getBean("cityDao");
dao.save(city);
}
}
控制台输出：
Jan 15, 2015 11:54:53 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3: display name [org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3]; startup date [Thu Jan 15 23:54:53 PKT 2015]; root of context hierarchy
Jan 15, 2015 11:54:53 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [HibernateConfig.xml]
Jan 15, 2015 11:54:53 PM org.springframework.context.support.AbstractApplicationContext obtainFreshBeanFactory
INFO: Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@b34bf3]: org.springframework.beans.factory.support.DefaultListableBeanFactory@1b8202e
Jan 15, 2015 11:54:53 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1b8202e: defining beans [dataSource,sessionFactory,cityDao]; root of factory hierarchy
Jan 15, 2015 11:54:53 PM org.springframework.jdbc.datasource.DriverManagerDataSource setDriverClassName
INFO: Loaded JDBC driver: com.mysql.jdbc.Driver
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
Jan 15, 2015 11:54:53 PM org.springframework.orm.hibernate3.LocalSessionFactoryBean buildSessionFactory
INFO: Building new Hibernate SessionFactory
抛出的异常是：
java.lang.NullPointerException
at com.testing.dao.CityDaoImpl.save(CityDaoImpl.java:19)
at com.testing.TestCityDao.test(TestCityDao.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access[=15=]0(ParentRunner.java:53)
at org.junit.runners.ParentRunner.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
您声明了 sessionFactory 依赖项：
<bean id="cityDao" class="com.testing.dao.CityDaoImpl">
<property name="sessionFactory" ref="sessionFactory"></property>
</bean>
然后你还有：
@Autowired
private SessionFactory sessionFactory;
尝试删除 @Autowired 注释，因为如果您使用 XML 配置，它是多余的。
仅仅因为你添加了sessionFactory，并不意味着Spring也可以自动管理Hibernate Sessions。
您还需要添加：
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
以及：
<tx:annotation-driven/>
现在您还需要将 @Transactional 添加到您的 save 例程中：
@Transactional
public void save(City city){
this.sessionFactory.getCurrentSession().save(city);
}