我创建了一个 DAO (ForecastPersistorDao.java)，它是接口及其对应的实现 (ForecastPersistorDaoImpl.java)。该实现有一个方法“persist()”，其工作是将一些数据持久保存到数据库中。当我尝试调用 persist 来持久化数据时，它会抛出 NullPointerException，因为它没有正确初始化 SessionFactory。请帮我指出我可能做错了什么：
ForecastPersistorDao.java
public interface ForecastPersistorDao {
void persist(List<ForecastedDemand> forecastedDemands);
List<DemandForecast> retrieveLastForecast(String marketplaceId);
}
ForecastPersistorDaoImpl.java
@Repository("forecastPersistorDao")
public class ForecastPersistorDaoImpl implements ForecastPersistorDao {
private SessionFactory sessionFactory;
@Autowired
public void setSessionFactory(SessionFactory sessionFactory) {
this.sessionFactory = sessionFactory;
}
/**
* Persist forecast in the database for later
*
* @param forecastedDemands
* List of forecast for all asin:marketplaceId tuple
*/
@Transactional
@Override
public void persist(List<ForecastedDemand> forecastedDemands) {
System.out.println("THIS IS ALWAYS NULL-------->>>>>>>> " + sessionFactory);
Session session = sessionFactory.getCurrentSession();
Date forecastCalculationDate = new Date();
// For each [asin:marketplace] tuple
for (ForecastedDemand forecastedDemand : forecastedDemands) {
String asin = forecastedDemand.getAsinMarketplaceId().getAsin();
String marketplaceId = forecastedDemand.getAsinMarketplaceId().getMarketplaceId();
String forecastingModel = forecastedDemand.getForecastingModel();
SortedMap<Instant, Double> forecast = forecastedDemand.getForecast();
// for each forecast date - write an entry in demand_forecasts table
for (Map.Entry<Instant, Double> entry : forecast.entrySet()) {
Date dateOfForecast = entry.getKey().toDate();
double quantityForecasted = entry.getValue();
DemandForecast forecastToPersist = new DemandForecast(asin, marketplaceId, forecastCalculationDate,
forecastingModel, quantityForecasted, dateOfForecast);
session.save(forecastToPersist);
}
}
}
主类（Runner.java）：
public final class FbsRunner {
private ForecastPersistorDao forecastPersistorDao;
public static void main(String[] args) {
Runner runner = new Runner();
runner.run();
}
public void run() {
ApplicationContext context =
new FileSystemXmlApplicationContext("spring-configuration/application-config.xml");
forecastPersistorDao = (ForecastPersistorDao) context.getBean("forecastPersistorDao"); // this works fine
System.out.println(">>>>>>>>>> forecastPersistorDao [this is fine (not null)]: " + forecastPersistorDao);
List<ForecastedDemand> forecastedDemand = [a list of Forecasted demand to be persisted int he DB]
// THE CALL BELOW FAILS...
forecastPersistorDao.persist(forecastedDemands);
System.out.println("Persisted demand in the database"); // We don't reach here.
}
}
弹簧配置/应用程序配置.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:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd
">
<!-- The main application context spring configuration -->
<import resource="application/hibernate.xml" />
<import resource="common/hibernate.xml" />
<!--<import resource="application/proxies.xml" />-->
<!--<import resource="common/aggregators.xml" /> -->
<import resource="application/environment.xml" />
<!--
Add any beans specific to your application here
-->
<bean id="forecastPersistorDao" class="com.amazon.fresh.fbs.dao.ForecastPersistorDaoImpl" />
</beans>
应用程序/hibernate.xml：
<bean id="SessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"
parent="AbstractSessionFactory" depends-on="EnvironmentHelper" >
<property name="hibernateProperties">
...
...
everything as expected
...
</bean>
常见/hibernate.xml：
<beans ... >
bean id="AbstractSessionFactory"
class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"
abstract="true">
<property name="mappingResources">
<list>
<value>com/amazon/fresh/fbs/dao/hibernate/RtipData.hbm.xml</value>
<value>com/amazon/fresh/fbs/dao/hibernate/Vendor.hbm.xml</value>
<value>com/amazon/fresh/fbs/dao/hibernate/AdjustmentPeriod.hbm.xml</value>
<value>com/amazon/fresh/fbs/dao/hibernate/DemandForecast.hbm.xml</value>
</list>
</property>
<property name="exposeTransactionAwareSessionFactory">
<value>true</value>
</property>
</bean>
<!-- Use Spring transactions for Hibernate -->
<tx:annotation-driven transaction-manager="txManager" mode='proxy' proxy-target-class='true'/>
<bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="SessionFactory" />
</bean>
<aop:aspectj-autoproxy/>
</beans>