最初使用Spring是为了解决业务层的事务管理问题。原先用手写代码发起、结束/回滚事务的做法碰到粗心的开发者很容易导致连接池的资源耗尽。Spring的声明性事务管理功能无疑是一剂良方。本文说明几种常见的配置方式及各自的优缺点。 方法一：BeanNameAutoProxyCreator 优点：有大量bean声明性事务管理时使用该方法可以简化配置 示例： <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd" > <beans>     <description>         Exploring spring Dependency Injection feature     </description>     <bean id="sessionFactory" class="org.springframework.orm.hibernate.LocalSessionFactoryBean">         <property name="configLocation">             <value>hibernate.cfg.xml</value>         </property>     </bean>     <bean id="transactionManager"         class="org.springframework.orm.hibernate.HibernateTransactionManager">         <property name="sessionFactory">             <ref local="sessionFactory"/>         </property>     </bean>     <!-- Transaction Interceptor set up to do PROPOGATION_REQUIRED on all methods -->     <bean id="matchAllTxInterceptor"         class="org.springframework.transaction.interceptor.TransactionInterceptor">         <property name="transactionManager">             <ref bean="transactionManager"/>         </property>         <property name="transactionAttributes">             <props>                 <prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>                 <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>                 <prop key="*">PROPAGATION_REQUIRED</prop>             </props>         </property>     </bean>     <!-- One BeanNameAutoProxyCreator handles all beans where we want all methods to use     PROPOGATION_REQUIRED -->     <bean id="hibInterceptor"         class="org.springframework.orm.hibernate.HibernateInterceptor">         <property name="sessionFactory">             <ref bean="sessionFactory"/>         </property>     </bean>     <bean id="autoProxyCreator"         class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">         <property name="interceptorNames">             <list>                 <idref local="matchAllTxInterceptor"/>                 <idref bean="hibInterceptor"/>             </list>         </property>         <property name="proxyTargetClass">             <value>true</value>         </property>         <property name="beanNames">             <list>                 <value>userDocumentManager</value>             </list>         </property>     </bean>     <bean id="docServerConfig" class="just.docserver.config.DocServerConfig" singleton="true">         <property name="config"><value>docsrv.conf</value></property>         <!-- contextPath is which url path the document server resides, KEEP it sync with actual deployment -->         <property name="contextPath"><value>/axis</value></property>     </bean>         <!--DAO classes definition begin-->     <bean id="docDao" class="just.docserver.dal.daoimpl.doc.DocDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="userFileDao" class="just.docserver.dal.daoimpl.doc.UserFileDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="docSettingDao" class="just.docserver.dal.daoimpl.doc.DocSettingDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="userDocumentDao" class="just.docserver.dal.daoimpl.doc.UserDocumentDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>         <property name="docDao"><ref local="docDao"/></property>         <property name="docSettingDao"><ref local="docSettingDao"/></property>         <property name="userFileDao"><ref local="userFileDao"/></property>     </bean>         <!--DAO classes definition end-->          <!--  Service definition begin -->     <bean id="userDocumentManager"         class="just.docserver.UserDocumentManagerImpl"         singleton="true">         <property name="docDao"><ref local="docDao"/></property>         <property name="docSettingDao"><ref local="docSettingDao"/></property>         <property name="userDocumentDao"><ref local="userDocumentDao"/></property>         <property name="userFileDao"><ref local="userFileDao"/></property>         <property name="docServerConfig"><ref local="docServerConfig"/></property>     </bean>     <!--  Service definition end --> </beans> 方法二：TransactionProxyFactoryBean 优点：配置灵活 示例： <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd" > <beans>     <description>         Exploring spring Dependency Injection feature     </description>     <bean id="sessionFactory" class="org.springframework.orm.hibernate.LocalSessionFactoryBean">         <property name="configLocation">             <value>hibernate.cfg.xml</value>         </property>     </bean>     <bean id="transactionManager"         class="org.springframework.orm.hibernate.HibernateTransactionManager">         <property name="sessionFactory">             <ref local="sessionFactory"/>         </property>     </bean>     <bean id="docServerConfig" class="just.docserver.config.DocServerConfig" singleton="true">         <property name="config"><value>docsrv.conf</value></property>         <!-- contextPath is which url path the document server resides, KEEP it sync with actual deployment -->         <property name="contextPath"><value>/axis</value></property>     </bean>         <!--DAO classes definition begin-->     <bean id="docDao" class="just.docserver.dal.daoimpl.doc.DocDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="userFileDao" class="just.docserver.dal.daoimpl.doc.UserFileDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="docSettingDao" class="just.docserver.dal.daoimpl.doc.DocSettingDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>     </bean>         <bean id="userDocumentDao" class="just.docserver.dal.daoimpl.doc.UserDocumentDaoImpl">         <property name="sessionFactory"><ref local="sessionFactory"/></property>         <property name="docDao"><ref local="docDao"/></property>         <property name="docSettingDao"><ref local="docSettingDao"/></property>         <property name="userFileDao"><ref local="userFileDao"/></property>     </bean>         <!--DAO classes definition end-->          <!--  Service definition begin -->   <bean id="userDocumentManagerTarget" class="just.docserver.UserDocumentManagerImpl">

      <property name="docDao"><ref local="docDao"/></property>

      <property name="docSettingDao"><ref local="docSettingDao"/></property>

      <property name="userDocumentDao"><ref local="userDocumentDao"/></property>

      <property name="userFileDao"><ref local="userFileDao"/></property>

      <property name="docServerConfig"><ref local="docServerConfig"/></property>

  </bean>

    <bean id="userDocumentManager" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">

      <property name="transactionManager">

        <ref local="transactionManager"/>

      </property>  

      <property name="target">

        <ref local="userDocumentManagerTarget"/>

      </property>

      <property name="proxyInterfaces"><value>just.docserver.UserDocumentManager</value></property>

      <property name="transactionAttributes">

        <props>

            <prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>

            <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>

            <prop key="*">PROPAGATION_REQUIRED</prop>

        </props>

      </property>

    </bean>    

    <!--  Service definition end -->

</beans>

但使用该方法配置时需要多配置一个xxxTarget的bean，该bean通常在应用用没有直接的用途，使得配置显得比较累赘。这一问题在高版本的spring中可以用嵌套的bean来解决。也就是将名为xxxTarget的bean直接写道被引用到的地方。按此方法，上例可以改成：

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"

>

<beans>

    <description>

        Exploring spring Dependency Injection feature

    </description>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate.LocalSessionFactoryBean">

        <property name="configLocation">

            <value>hibernate.cfg.xml</value>

        </property>

    </bean>

    <bean id="transactionManager"

        class="org.springframework.orm.hibernate.HibernateTransactionManager">

        <property name="sessionFactory">

            <ref local="sessionFactory"/>

        </property>

    </bean>

    <bean id="docServerConfig" class="just.docserver.config.DocServerConfig" singleton="true">

        <property name="config"><value>docsrv.conf</value></property>

        <!-- contextPath is which url path the document server resides, KEEP it sync with actual deployment -->

        <property name="contextPath"><value>/axis</value></property>

    </bean>    

    <!--DAO classes definition begin-->

    <bean id="docDao" class="just.docserver.dal.daoimpl.doc.DocDaoImpl">

        <property name="sessionFactory"><ref local="sessionFactory"/></property>

    </bean>    

    <bean id="userFileDao" class="just.docserver.dal.daoimpl.doc.UserFileDaoImpl">

        <property name="sessionFactory"><ref local="sessionFactory"/></property>

    </bean>    

    <bean id="docSettingDao" class="just.docserver.dal.daoimpl.doc.DocSettingDaoImpl">

        <property name="sessionFactory"><ref local="sessionFactory"/></property>

    </bean>    

    <bean id="userDocumentDao" class="just.docserver.dal.daoimpl.doc.UserDocumentDaoImpl">

        <property name="sessionFactory"><ref local="sessionFactory"/></property>

        <property name="docDao"><ref local="docDao"/></property>

        <property name="docSettingDao"><ref local="docSettingDao"/></property>

        <property name="userFileDao"><ref local="userFileDao"/></property>

    </bean>    

    <!--DAO classes definition end-->

    

    <!--  Service definition begin -->

    <bean id="userDocumentManager" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">

      <property name="transactionManager">

        <ref local="transactionManager"/>

      </property>  

      <property name="target">

          <bean class="just.docserver.UserDocumentManagerImpl">

              <property name="docDao"><ref local="docDao"/></property>

              <property name="docSettingDao"><ref local="docSettingDao"/></property>

              <property name="userDocumentDao"><ref local="userDocumentDao"/></property>

              <property name="userFileDao"><ref local="userFileDao"/></property>

              <property name="docServerConfig"><ref local="docServerConfig"/></property>

          </bean>

      </property>

      <property name="proxyInterfaces"><value>just.docserver.UserDocumentManager</value></property>

      <property name="transactionAttributes">

        <props>

            <prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>

            <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>

            <prop key="*">PROPAGATION_REQUIRED</prop>

        </props>

      </property>

    </bean>    

    <!--  Service definition end -->

</beans>

这样整个配置更为简洁清晰，而且更适合于代码生成工具来生成这些配置，进一步提高开发效率。

总结：

本文归纳了Spring声明性事务配置几种方式，BeanNameAutoProxyCreator，TransactionProxyFactoryBean即TransactionProxyFactoryBean加嵌套式Target bean。方法一适用于有大量bean需要声明性事务配置的情形。方法二、三配置更加灵活。方法三比方法二更加简洁、紧凑，十分适用于代码生成。另外，方法有个缺点，如果bean实现某些接口，使用方法一无法指定对这些接口进行截获(利用ProxyFactoryBean的proxyInterfaces属性)，从而无法使用JDK的动态代理，只能使用CGLIB来实现方法截获。