上篇说了aop的配置，并且说了spring事务管理是基于aop的，那么Spring声明式事务的配置就有两种方式：XML配置及注解配置
　　不多说，直接看配置文件
　　一、配置文件
　　applicationContext-transaction.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd ">
<bean id="transactionManager" class="org.springframework.orm.hibernate5.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
<!-- 通知 -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<!-- 传播行为 -->
<tx:method name="save*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="insert*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="list*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="get*" propagation="SUPPORTS" read-only="true"/>
</tx:attributes>
</tx:advice>
<!-- aop -->
<aop:config>
<aop:advisor advice-ref="txAdvice" pointcut="execution(* com.mango.jtt.service.*.*(..))"/>
</aop:config>
<!-- 注解管理事务 -->
<tx:annotation-driven transaction-manager="transactionManager"/>
</beans>
　　注解管理事务以上都是xml配置的事务，基于注解的事务，只需配置<tx:annotation-driven/>标签，然后在Spring bean中添加@Transational注解即可实现事务管理。
　　二，Spring事务管理本质
　　Spring并不直接管理事务，而是提供多种事务管理器，他们讲事务管理的职责委托给JAT或其他持久化机制所提供的平台相关的事务实现。上述配置文件中就是利用的hibernate事务管理器实现的Hibernate事务管理。详细信息不说，想事务属性什么的，具体可参考spring in action及spring官方文档
　　三、继续说下事务对getCurrentSession的影响
　　在Spring实战篇系列----源码解析SessionFactory及Session的管理及getCurrentSession的使用 文章中说了getCurrentSession是要基于事务的，才能实现session的生命周期的管理。那么Spring的事务管理到底做了什么。
　　首先看事务管理器HibernateTransactionManager，它并没有做太多工作，一个空的构造函数及
/**
* Create a new HibernateTransactionManager instance.
* A SessionFactory has to be set to be able to use it.
* @see #setSessionFactory
*/
public HibernateTransactionManager() {
}
　　及afterPropertiesSet()方法
@Override
public void afterPropertiesSet() {
if (getSessionFactory() == null) {
throw new IllegalArgumentException("Property 'sessionFactory' is required");
}
if (this.entityInterceptor instanceof String && this.beanFactory == null) {
throw new IllegalArgumentException("Property 'beanFactory' is required for 'entityInterceptorBeanName'");
}
// Check for SessionFactory's DataSource.
if (this.autodetectDataSource && getDataSource() == null) {
DataSource sfds = SessionFactoryUtils.getDataSource(getSessionFactory());
if (sfds != null) {
// Use the SessionFactory's DataSource for exposing transactions to JDBC code.
if (logger.isInfoEnabled()) {
logger.info("Using DataSource [" + sfds +
"] of Hibernate SessionFactory for HibernateTransactionManager");
}
setDataSource(sfds);
}
}
}

　　可见事务管理器的初始化并没有做太多工作。那么看事务管理对其的影响，先看调用栈
TransactionSynchronizationManager.initSynchronization() line: 269
HibernateTransactionManager(AbstractPlatformTransactionManager).prepareSynchronization(DefaultTransactionStatus， TransactionDefinition) line: 542
HibernateTransactionManager(AbstractPlatformTransactionManager).prepareTransactionStatus(TransactionDefinition， Object， boolean， boolean， boolean， Object) line: 513
HibernateTransactionManager(AbstractPlatformTransactionManager).getTransaction(TransactionDefinition) line: 393
TransactionInterceptor(TransactionAspectSupport).createTransactionIfNecessary(PlatformTransactionManager， TransactionAttribute， String) line: 426
TransactionInterceptor(TransactionAspectSupport).invokeWithinTransaction(Method， Class<?>， InvocationCallback) line: 275
TransactionInterceptor.invoke(MethodInvocation) line: 96
ReflectiveMethodInvocation.proceed() line: 179
ExposeInvocationInterceptor.invoke(MethodInvocation) line: 92
ReflectiveMethodInvocation.proceed() line: 179
JdkDynamicAopProxy.invoke(Object， Method， Object[]) line: 213
$Proxy316.getOrderById(String) line: not available
OrderController.orderPay(String， Model) line: 84
　　从调用栈可以看出，只要在连接点处配置了事务管理，首先都会走到initSynchronization()。
/**
* Activate transaction synchronization for the current thread.
* Called by a transaction manager on transaction begin.
* @throws IllegalStateException if synchronization is already active
*/
public static void initSynchronization() throws IllegalStateException {
if (isSynchronizationActive()) {
throw new IllegalStateException("Cannot activate transaction synchronization - already active");
}
logger.trace("Initializing transaction synchronization");
synchronizations.set(new LinkedHashSet<TransactionSynchronization>());
}
　　最终会在synchronizations中set进new LinkedHashSet<TransactionSynchronization>()，从而isSynchronizationActive()为true
/**
* Return if transaction synchronization is active for the current thread.
* Can be called before register to avoid unnecessary instance creation.
* @see #registerSynchronization
*/
public static boolean isSynchronizationActive() {
return (synchronizations.get() != null);
}
　　因此这里也就解释了上上篇留下的疑问，为什么配置了事务管理，就不会抛异常了。其实只有配置了事务，session就会在事务提交或者回滚后关闭
SessionImpl.close() line: 402
SessionFactoryUtils.closeSession(Session) line: 167
SpringSessionSynchronization.afterCompletion(int) line: 138
TransactionSynchronizationUtils.invokeAfterCompletion(List<TransactionSynchronization>， int) line: 168
HibernateTransactionManager(AbstractPlatformTransactionManager).invokeAfterCompletion(List<TransactionSynchronization>， int) line: 1001
HibernateTransactionManager(AbstractPlatformTransactionManager).triggerAfterCompletion(DefaultTransactionStatus， int) line: 976
HibernateTransactionManager(AbstractPlatformTransactionManager).processCommit(DefaultTransactionStatus) line: 806
HibernateTransactionManager(AbstractPlatformTransactionManager).commit(TransactionStatus) line: 730
TransactionInterceptor(TransactionAspectSupport).commitTransactionAfterReturning(TransactionAspectSupport$TransactionInfo) line: 483
TransactionInterceptor(TransactionAspectSupport).invokeWithinTransaction(Method， Class<?>， InvocationCallback) line: 290
TransactionInterceptor.invoke(MethodInvocation) line: 96
ReflectiveMethodInvocation.proceed() line: 179
ExposeInvocationInterceptor.invoke(MethodInvocation) line: 92
ReflectiveMethodInvocation.proceed() line: 179
JdkDynamicAopProxy.invoke(Object， Method， Object[]) line: 213
$Proxy316.getOrderById(String) line: not available
OrderController.orderPayInfo(String， Model) line: 72