Service层进行事务管理，Dao层获得session进行事务处理抛异常的情况

1. spirng中配置service层的事务管理

在一个web项目中，如果使用SSH框架，一般在spring中配置事务管理。我们一般不会在dao层使用transaction，事务被配置在service层上更为合理，因为业务层方法表示逻辑上的一个原子操作。

spring中配置service层的事务管里，配置文件中的配置如下：

      <bean id="txProxy"
         class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
        <property name="beanNames">
          <list>
             <value>*Service</value> //这里表示
          </list>
        </property>
        <property name="interceptorNames">
          <list>
             <value>transactionInterceptor</value>
          </list>
        </property>
   </bean>

<bean id="txManager"
class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>


    <bean id="transactionInterceptor" class="org.springframework.transaction.interceptor.TransactionInterceptor">
            <property name="transactionManager">
                  <ref bean="txManager" />
           </property> 
       <property name="transactionAttributes">
          <props>
            <prop key="delete*">PROPAGATION_REQUIRED,-Exception</prop>
            <prop key="update*">PROPAGATION_REQUIRED,-Exception</prop>
            <prop key="add*">PROPAGATION_REQUIRED,-Exception</prop>
            <prop key="save*">PROPAGATION_REQUIRED,-Exception</prop>
            <prop key="query*">PROPAGATION_REQUIRED,readOnly</prop>
            <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
            <prop key="create*">PROPAGATION_REQUIRED,-Exception</prop>
          </props>
       </property>
     </bean>

2，我尝试在Dao层获取sesssion，然后进行事务处理。代码如下

Session session=manureDao.getHibernateTemplate().getSessionFactory().getCurrentSession();
session.beginTransaction();
ManureInfo manureInfo=(ManureInfo)session.load(ManureInfo.class, 15);
System.out.println( manureInfo.getAreaNum());
session.getTransaction().commit();
session.close();

然后报以下异常：

org.hibernate.HibernateException: No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here
at org.springframework.orm.hibernate3.SpringSessionContext.currentSession(SpringSessionContext.java:63)
at org.hibernate.impl.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:687)
at cn.sinobest.scscms.test.process.TestManure.testUpdateManureInfo(TestManure.java:81)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:274)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:48)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:242)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:58)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:240)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:48)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:233)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:31)
at org.junit.runners.ParentRunner.run(ParentRunner.java:303)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

原因：使用sessionfactory.getcurrentsession执行hibernate操作时，hibernate的操作默认必须包含在一个transaction中，

也就是开始要用session.begiontransaction得到一个transaction 实例(譬如tx), 操作结束时在这个实例上进行事务的

提交tx.commit或回滚tx.rollback. 如果这些crud操作不被包括在一个具体的transaction中，hibernate就会抛出上述异常。