我使用spring + hibernate创建了一个应用程序，但始终会收到此错误。这是我第一个使用hibernate的应用程序，我阅读了一些指南，但无法解决此问题。我在哪里做错了？
这是我的应用程序的代码
ott 05, 2014 4:03:06 PM org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
Informazioni: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1eab16b: startup date [Sun Oct 05 16:03:06 CEST 2014]; root of context hierarchy
ott 05, 2014 4:03:06 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
Informazioni: Loading XML bean definitions from class path resource [springConfig.xml]
ott 05, 2014 4:03:08 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.5.Final}
ott 05, 2014 4:03:08 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.3.6.Final}
ott 05, 2014 4:03:08 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
ott 05, 2014 4:03:08 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
ott 05, 2014 4:03:09 PM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
ott 05, 2014 4:03:09 PM org.hibernate.engine.transaction.internal.TransactionFactoryInitiator initiateService
INFO: HHH000399: Using default transaction strategy (direct JDBC transactions)
ott 05, 2014 4:03:09 PM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init>
INFO: HHH000397: Using ASTQueryTranslatorFactory
Exception in thread "main" org.hibernate.HibernateException: Could not obtain transaction-synchronized Session for current thread
at org.springframework.orm.hibernate4.SpringSessionContext.currentSession(SpringSessionContext.java:134)
at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:1014)
at coreservlets.StudentDAOImpl.create(StudentDAOImpl.java:19)
at coreservlets.MainApp.main(MainApp.java:14)