Spring声明性事务配置几种方式

 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。