上篇說了aop的配置，並且說了Spring事務管理是基於aop的，那麼Spring宣告式事務的配置就有兩種方式：XML配置及註解配置

不多說，直接看配置檔案

一、配置檔案

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>
			<!-- 傳播行為 -->
			<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>

	<!-- 註解管理事務 -->
	<tx:annotation-driven transaction-manager="transactionManager"/>
</beans>
 

註解管理事務以上都是xml配置的事務，基於註解的事務，只需配置<tx:annotation-driven/>標籤，然後在Spring bean中新增@Transational註解即可實現事務管理。

二，Spring事務管理本質

Spring並不直接管理事務，而是提供多種事務管理器，他們講事務管理的職責委託給JAT或其他持久化機制所提供的平臺相關的事務實現。上述配置檔案中就是利用的Hibernate事務管理器實現的Hibernate事務管理。詳細資訊不說，想事務屬性什麼的，具體可參考spring in action及spring官方文件

三、繼續說下事務對getCurrentSession的影響

首先看事務管理器HibernateTransactionManager，它並沒有做太多工作，一個空的建構函式及

/**
	 * 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);
			}
		}
	}
 

可見事務管理器的初始化並沒有做太多工作。那麼看事務管理對其的影響，先看呼叫棧

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	

從呼叫棧可以看出，只要在連線點處配置了事務管理，首先都會走到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>());
	}

/**
	 * 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);
	}

因此這裡也就解釋了上上篇留下的疑問，為什麼配置了事務管理，就不會拋異常了。其實只有配置了事務，session就會在事務提交或者回滾後關閉

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